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First forms - class-VI

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Convert the following fraction into simple decimal recurring form.

$\displaystyle \frac{1}{6}$= ?

  1. $0.1\bar 9$

  2. $0.1\bar 6$

  3. $0.1\bar 4$

  4. $0.1\bar 3$


Correct Option: B
Explanation:
    Pure recurring decimal is a decimal fraction in which all the figures after the decimal point are repeated.
    $\displaystyle \frac { 1 }{ 6 }= 0.6666666666..$ is $ 0.\overset { \ _ \ _  }{ 6 } $.

Find whether it is a terminating or a non-terminating decimal.

$2.4 \div 0.072$.

  1. Terminating

  2. Non-terminating

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

A terminating decimal is a decimal that ends. It's a decimal with a finite number of digits.

$2.4\div 0.072=33.3333333333....$.
The division gives recurring factor.
Hence, it is a non-terminating decimal.

Express $\displaystyle \frac{4}{9}$ as recurring decimal 

  1. $0.\bar 5$

  2. $0.\bar 4$

  3. $0.\overline {45}$

  4. $0.\overline {54}$


Correct Option: B
Explanation:

On dividing 4 by 9 we get

$\dfrac { 4 }{ 9 } =0.4444......$
So, correct answer is option B.

Find whether it is a terminating or a non-terminating decimal.

$3.2 \div 2.24$.

  1. Terminating

  2. Non-terminating

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

A terminating decimal is a decimal that ends. It's a decimal with a finite number of digits.

$3.2\div 2.24= 1.428571429....$.
The division does not gives end result.
Hence, it is a non-terminating decimal.

Find whether it is a terminating or a non-terminating decimal.

$0.3 \div 0.09$.

  1. Terminating

  2. Non-terminating

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

A terminating decimal is a decimal that ends. It's a decimal with a finite number of digits.

$0.3\div 0.09= 3.33333333333333...$. 
The division results in recurring factor.
Hence it is a non terminating decimal.

The rational number which can be expressed as a terminating decimal is

  1. $\displaystyle \frac{1}{6}$

  2. $\displaystyle \frac{1}{12}$

  3. $\displaystyle \frac{1}{15}$

  4. $\displaystyle \frac{1}{20}$


Correct Option: D
Explanation:

A terminating decimal is a decimal that ends. It's a decimal with a finite number of digits. 
$\displaystyle \frac {1}{20}= 0.05$ 

In the other options, the decimal does not end with a finite number of digits.

Without actually performing the long division, state whether the following rational number will have a terminating decimal expansion or non -terminating decimal expansion

$\displaystyle \frac{15}{1600}$

  1.  Terminating decimal expansion

  2.  Non-terminating decimal expansion

  3. Cannot be determined

  4. None


Correct Option: A
Explanation:

Factorize the denominator we get $1600=2 \times 2 \times 2 \times2 \times 2 \times 2 \times 5 \times 5  = 2^{6} \times 5^{2}$
so denominator is in form of $2^n \times 5^m$
Hence $\frac{15}{1600}$  is  terminating.

Which of the following is terminating decimal?
$\cfrac{23}{90}, \cfrac{111}{148}, \cfrac{29}{145}, \cfrac{1}{6}$

  1. $\cfrac{111}{148}$

  2. $\cfrac{23}{90}$

  3. $\cfrac{29}{145}$

  4. $\cfrac{1}{6}$


Correct Option: A,C
Explanation:

$\cfrac{111}{148}$  is having terminating decimal $0.75$

$\dfrac{29}{145}$ is having terminating decimal $0.2$

Decimal form of $\displaystyle \frac{3888} {1000} $ 

  1. 38.88

  2. 3.888

  3. 388.8

  4. .3888


Correct Option: B
Explanation:

correct option is B..

What is the 25th digit to the right of the decimal point in the decimal form of $\displaystyle \frac { 6 }{ 11 } $?

  1. $3$

  2. $4$

  3. $5$

  4. $6$

  5. $7$


Correct Option: C
Explanation:

$\cfrac{6}{11}$ $=$ $ 0.545454....$ 

The result is a non-terminating, non-recurring number whose odd digit is $5$ and even digit is $4$.
Thus, 25th digit from the decimal point will be $5$ (option C).

Without actually performing the long division, state whether the following rational number will have a terminating decimal expansion or non -terminating decimal expansion

$\displaystyle \frac{7}{210}$

  1. Terminating decimal expansion

  2. Non -terminating decimal expansion

  3. Cannot be determined

  4. None


Correct Option: B
Explanation:

Simplify it by dividing nominator and denominator both by 7 we get $\frac{1}{30}$
Factorize the denominator we get  $30=2 \times 3 \times 5$
Denominator has 3 also in denominator
So denominator is not in form of $2^{n} \times 5^{n}$
 
Hence it is non terminating.

If $\displaystyle d=\frac { 1 }{ { 2 }^{ 3 }\times { 5 }^{ 7 } } $ is expressed as a terminating decimal, how many non zero digits will d have?

  1. One

  2. Two

  3. Three

  4. Seven

  5. Ten


Correct Option: B
Explanation:
d = $\cfrac{1}{2^3\times5^7 } $
Multiply by $\cfrac{2^4}{2^4}$  
$\Rightarrow$ d = $\cfrac{2^4}{2^3 \times 5^7 \times 2^4}$
= $\cfrac{16}{2^7 \times 5^7 }$
= $\cfrac{16}{10^7 }$
=$0.0000016 $
Hence, d will have two non-zero digits, 16, when expressed as a decimal.
Answer: B.

$0.\overline{585}$ is equal to

  1. $\displaystyle\frac{585}{99}$

  2. $\displaystyle\frac{585}{999}$

  3. $\displaystyle\frac{999}{585}$

  4. none of these


Correct Option: B
Explanation:

Given that, $0.\overline{585}$.

Let,

$ x=0.\overline{585} $

$ x=0.585585585........ $

 

Multiply by 1000 on both sides,

$ 1000x=1000\times 0.585585585........ $

$ =585.585585585.... $

$ =585+0.585585585........ $

$ 1000x=585+x $

$ 999x=585 $

$ x=\dfrac{585}{999} $

 

Hence, this is the answer.

A terminating decimal has a ............ number of terms after the decimal point.

  1. zero

  2. infinite

  3. finite

  4. none of the above


Correct Option: C
Explanation:

A terminating decimal is a decimal that ends. It's a decimal with a finite number of digits.
Therefore, $C$ is the correct answer.

As the decimal of $\dfrac {1}{3}$ repeats$,$ $\dfrac {1}{3}$ is a $.........$ decimal.

  1. exact

  2. negative

  3. terminating

  4. non-terminating


Correct Option: D
Explanation:

$\dfrac {1}{3} = 0.33333333333333333333333333....$ 

It is non-terminating recurring decimal.
Therefore, $D$ is the correct answer.

If the quotient is terminating decimal, the division is complete only when ...............

  1. we get the remainder $1$

  2. we get the remainder zero

  3. we get the remainder as the repeated numbers

  4. All of the above


Correct Option: B
Explanation:
Any division is complete only when we get the remainder zero.
Therefore, $B$ is the correct answer.

A ............. decimal representation can be repeating or non-repeating decimal

  1. real

  2. non-terminating

  3. terminating

  4. none of these


Correct Option: B
Explanation:

A non- terminating representation can be repeating $\dfrac{7}{22} = 0.31818181....$
or non-repeating decimal $\pi = 3.1415....$
Therefore, $B$ is the correct answer.

Which option will have a terminating decimal expansion?

  1. $\dfrac {77}{210}$

  2. $\dfrac {23}{30}$

  3. $\dfrac {125}{441}$

  4. $\dfrac {23}{8}$


Correct Option: D
Explanation:

The decimal expansion of a number may terminate in which case the number is called a regular number or finite decimal. In the given options:

a. $\dfrac{77}{210} = 0.366666666....... \; or  \; 0.3\bar6$

b. $\dfrac{23}{30} = 0.766666666....... \; or  \; 0.7\bar6$

c. $\dfrac{125}{441} = 0.283446712......$ i.e. it goes on infintely

d. $\dfrac{23}{8} = 2.875$

A number having non-terminating and recurring decimal expansion is.

  1. An integer

  2. A rational number

  3. An irrational number

  4. A whole number


Correct Option: B
Explanation:

A number having non-terminating and recurring decimal expansion is  a Rational Number


for example 

$\dfrac{2}{7}$  is a rational number 

$\dfrac{2}{7} =0.285714285714285714.......... $

or   $\dfrac{2}{7} =\overline{0.285714}.......... $

the number has non-terminating decimal expansion but recurring after every 6 digits after decimal

So option $B $ is correct

$1.23 \bar{48}$ is:

  1. An integer

  2. A rational number

  3. An irrational number

  4. A natural number


Correct Option: B
Explanation:

$1.23\bar{48}$ can be written as $1.23484848484848....$ and so on 

Hence this is a recurring decimal as decimal part is repeating after one-thousand's place.
Thus, it is a rational number.

Which of the following numbers has the terminating decimal representation?

  1. $\displaystyle \frac{1}{7}$

  2. $\displaystyle \frac{1}{3}$

  3. $\displaystyle \frac{3}{5}$

  4. $\displaystyle \frac{17}{3}$


Correct Option: C
Explanation:

$\dfrac{3}{5} = 0.6$ which is terminating decimal. 


$\dfrac{1}{7} = 0.142857.....$

$\dfrac{1}{3} = 0.333......$

$\dfrac{17}{3} = 5.6666......$

Show the correct sequence of the given four option in ascending order
(1) Prime minister  (2) Chief Minister  (3) Mayor  (4) President  (5) Sarpanch

  1. $5,3,2,4,1$

  2. $5,2,3,4,1$

  3. $5,3,2,1,4$

  4. $5,4,2,1,3$


Correct Option: C
Explanation:
In ascending order 
Sarpanch < Mayore < Chief Minister < Prime minister < President.
$\therefore$ Option $ C$  is the correct answer.

$3.24636363....$ is _____________.

  1. An integer

  2. An irrational number

  3. A rational number

  4. Not a real number


Correct Option: C
Explanation:

$3.24636363.......$ is a non-terminating, but repeating number as after one-hundredth place, digits are recurring.

$\therefore$ It is a rational number.

$\dfrac{p}{q}$ form of the number $0.\overline{3}$ is :

  1. $\dfrac{3}{10}$

  2. $\dfrac{3}{100}$

  3. $\dfrac{1}{3}$

  4. $\dfrac{1}{2}$


Correct Option: C
Explanation:

Let $x$ = .33333......

Multiplying by 10 on both sides we get
$10x=3.3333....\ on\quad subtracting\quad both\quad equations\quad we\quad get,\ 9x=3\ x=\dfrac { 1 }{ 3 } $
So, correct answer is option C.

$\dfrac{35}{50}$ has a non-terminating decimal expansion.

  1. True

  2. False


Correct Option: B
Explanation:

$35/50=7/10=0.7$
This is a terminating decimal number.

The decimal representation of $\dfrac { 93 }{ 1500 }$  will be

  1. Terminating

  2. Non-terminating

  3. Non-terminating, repeating

  4. Non-terminating, non-repeating


Correct Option: A
Explanation:

Checking the termination of $\cfrac{93}{1500}$ is same as checking the termination of $\cfrac{31}{500}$ which is equal to $\cfrac{62}{1000}$


As the value is $0.062$, we can say the fraction is terminating.

$\therefore \cfrac{93}{1500}$ is terminating.

The fraction, $\dfrac{1}{3}$

  1. equals $0.33333333$

  2. is less than $0.33333333\ by\ \dfrac{1}{3.10^{8}}$

  3. is less than $0.33333333\ by\ \dfrac{1}{3.10^{9}}$

  4. is greater than $0.33333333\ by\ \dfrac{1}{3.10^{8}}$

  5. is greater than $0.33333333\ by\ \dfrac{1}{3.10^{9}}$


Correct Option: D
Explanation:

$\cfrac { 1 }{ 3 } -0.33333333=\cfrac { 1 }{ 3 } -\cfrac { 33333333 }{ { 10 }^{ 8 } } \ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad =\cfrac { { 10 }^{ 8 }-99999999 }{ 3\cdot { 10 }^{ 8 } } \ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad =\cfrac { 1 }{ 3\cdot { 10 }^{ 8 } } $

$\therefore \cfrac { 1 }{ 3 } $ is greater than 0.33333333 by $\cfrac { 1 }{ 3\cdot { 10 }^{ 8 } } $.

Let $x=\dfrac { p }{ q } $ be a rational number, such that the prime factorization of $q$ is of the form $2^n 5^m$, where $n, m$ are non-negative integers. Then $x$ has a decimal expansion which terminates.

  1. True

  2. False

  3. Neither

  4. Either


Correct Option: A
Explanation:

The form of q is $2^n*5^m$
q can be $1,2,5,10,20,40....$
Any integer divided by these numbers will always give a terminating decimal number.

Without actually performing the long division, state whether the following rational number will have terminating decimal expansion or a non-terminating repeating decimal expansion. Also, find the numbers of places of decimals after which the decimal expansion terminates.
$\dfrac { 13 }{ 3125 } $

  1. $3$

  2. $4$

  3. $5$

  4. $6$


Correct Option: C
Explanation:

The given value is $\dfrac{13}{3125}$ the denominator is 3125 which can be written as:


$3125=2^0 \times 5^5$ it is in the form of $2^m \times 5^n$

$max(m,n)=5$

$\therefore$ the expansion is terminating decimal it terminates after 

$max(m,n)=5$ places from the decimal [since  $ m=0,n=5$]

State whether the following statement is true/false.

$\dfrac{2375}{375}$ is not a terminating decimal

  1. True

  2. False


Correct Option: A
Explanation:

For $\cfrac{2375}{375}$


$375=5^3\times 3$ and $2375=5^3\times 19$


Since, denominator contains $3$ as a factor other than only $2$ or $5$,

So, $\cfrac{2375}{375}$ is is non terminating.

$9.1 \overline { 7 }$ is

  1. Terminating decimal

  2. Mixed repeating decimal

  3. Pure repeating decimal

  4. None of these


Correct Option: C
Explanation:

Given 


$9.1\bar 7$

Here the bar representation implies that the decimal is purely repeating one 

$\implies 9.1\bar 7=9.17777777777777777777777.....$

$\dfrac { 317 } { 3125 }$  represents ______.

  1. A terminating decimal

  2. A non-recurring decimal

  3. A recurring decimal

  4. An Integer


Correct Option: A

If $x=0.123\bar{4}, y=0.12\bar{34}$ and $z=0.1\bar{234}$, then which of the following is correct?

  1. $x>y>z$

  2. $y$

  3. $z>x$

  4. $x>z>y$


Correct Option: D

Without doing any actual division, find which of the following rational numbers have terminating decimal representation :
(i) $\displaystyle \dfrac{7}{16}$ (ii) $\displaystyle \dfrac{23}{125}$
(iii) $\displaystyle \dfrac{9}{14}$ (iv) $\displaystyle \dfrac{32}{45}$
(v) $\displaystyle \dfrac{43}{50}$ (vi) $\displaystyle \dfrac{17}{40}$
(vii) $\displaystyle \dfrac{61}{75}$ (viii) $\displaystyle \dfrac{123}{250}$

  1. (i), (iii), (v), (vi) and (vii)

  2. (i), (ii), (v), (vi) and (viii)

  3. (i), (iii), (v), (vi) and (viii)

  4. (i), (ii), (v), (vi) and (vii)


Correct Option: B
Explanation:

 The rational no having denominator $3, 7, 9, 11, 13, 17, 23, 27$.............. and multiple of these number will have non terminating decimal .
(1) $\dfrac{7}{16}$ the denominator of this rational number is not having these above number and multiple of these number, so this will have  terminating decimal.
(2) $\dfrac{23}{125}$ -- the denominator of this rational number is not having these above number and multiple of these number, so this will have  terminating decimal.
(3) $\dfrac{9}{14}$ --he denominator of this rational number is having these above number multiple of $7$, so this will have non terminating decimal.
(4)$\dfrac{32}{45}$--he denominator of this rational number is having these above number multiple of 9, so this will have non terminating decimal.
(5) $\dfrac{43}{50}$-- the denominator of this rational number is not having these above number and multiple of these number, so this will have  terminating decimal.
(6)$\dfrac{17}{40}$ -- the denominator of this rational number is not having these above number and multiple of these number, so this will have  terminating decimal.
(7)$\dfrac{61}{75}$-- he denominator of this rational number is having these above number multiple of 3, so this will have non terminating decimal.
(8)$\dfrac{123}{250}$--the denominator of this rational number is not having these above number and multiple of these number, so this will have  terminating decimal.
(i), (ii), (v), (vi) and (viii) will have  terminating decimal.

A rational number in its decimal expansion is $327.7081.$ What can you say about the prime factors of $q$, when this number is expressed in the form $\cfrac {p}{q}$?

  1. $q$ has prime factors $2$ or $5$ or both.

  2. $q$ has prime factors except $2$ and $5.$

  3. $q$ has no prime factors

  4. None of these


Correct Option: A
Explanation:

We know that The rational no having denominator 3, 7, 9, 11, 13, 17, 23, 27.............. and multiple of these number will have non terminating decimal .
As  decimal expansion is 327.7081 which is terminating.
prime factors of q, when this number is expressed in the form p/q will not be above number, it will be 2 or 5 or both.

Consider the following statements :
1. $\displaystyle \frac{1}{22}$ can not be written as terminating decimal 


2. $\displaystyle \frac{2}{15}$ can be written as a terminating decimal 

3. $\displaystyle \frac{1}{16}$ can be written as a terminating decimal 

Which of the statements given above is/are correct ?

  1. $1$ only

  2. $2$ only

  3. $1$ and $3$

  4. $2$ and $3$


Correct Option: C
Explanation:

$\displaystyle \frac{1}{22} = 0.04545454545$ is not a terminating decimal.

$\displaystyle \frac{2}{15}  = 0.133333333$ is not a terminating decimal.

$\displaystyle \frac{1}{16} = 0.0625$ is a terminating decimal.

Hence, statement $1$ and $3$ are correct.

Which one of the following is not a correct statement ?

  1. $\displaystyle 0.\overline{01}=\frac{1}{90}$

  2. $\displaystyle 0.\overline{1}=\frac{1}{9}$

  3. $\displaystyle 0.\overline{2}=\frac{2}{9}$

  4. $\displaystyle 0.\overline{3}=\frac{1}{3}$


Correct Option: A
Explanation:

$\dfrac{1}{90} = 0.0111111111 = 0.0\bar{1}$


$\dfrac{1}{9} = 0.11111111 = 0.\bar{1}$

$\dfrac{2}{9} = 0.222222222 = 0.\bar{2}$

$\dfrac{1}{3} = 0.3333333333= 0.\bar{3}$

Hence, option $A$ is not correct.

The decimal form of $5\dfrac{3}{8}$ is

  1. $5.375$

  2. $5.000$

  3. $5.255$

  4. $2.325$


Correct Option: A
Explanation:

First change the mixed fraction into proper fraction.
$5\dfrac{3}{8}=\dfrac{43}{8}$

$\dfrac{43}{8}= 5 + \dfrac38 = 5 + 0.375 = 5.375$

Arrange the following decimal numbers in ascending order.
$5.5, 0.55, 0.055, 0.005$

  1. $5.5, 0.055, 0.005, 0.55$

  2. $0.55, 0.005, 0.055, 5.5$

  3. $5.5, 0.55, 0.055, 0.005$

  4. $0.005, 0.055, 0.55, 5.5$


Correct Option: D
Explanation:

We need to arrange the numbers from smallest to largest.
So, $0.005, 0.055, 0.55, 5.5$ is in ascending order

............... numbers have terminating and non- terminating repeating decimals.

  1. Integers

  2. Whole

  3. Rational

  4. Irrational


Correct Option: C
Explanation:

$\dfrac {1}{4} = 0.25$ is a terminating decimal.


$\dfrac {8}{3} = 2.666666666......$ is a non-terminating repeating decimal.

Both are rational numbers but it was non repeating then they are irrational numbers.
Therefore, $C$ is the correct answer.

If the denominator of a fraction has factors other then $2$ and $5$, the decimal expression ..............

  1. repeats

  2. is that of a whole number

  3. has equal numerator and denominator

  4. terminates


Correct Option: A
Explanation:

If there are prime factors in the denominator other than $2$ or $5$, then the decimals repeat.
$\dfrac {1}{24} = \dfrac {1}{3\times 2\times 2\times 2}$ (there is a factor of $3$, the decimal will repeat.)
Therefore, $A$ is the correct answer.

If the denominator of a fraction has only factors of $2$ and factors of $5$, the decimal expression ............. 

  1. has equal numerator and denominator

  2. becomes a whole number

  3. does not terminate

  4. terminates


Correct Option: D
Explanation:

When the prime factorization of the denominator of a fraction has only factors of $2$ and factors of $5$, we can always express the decimal as terminating decimal. 
For examples $\dfrac {1}{25} = \dfrac {1}{5\times 5}$ repeats (just powers of $5$, the decimal terminates.)
Therefore, $D$ is the correct answer.

$\dfrac {1}{2} = 0.5$
It is a terminating decimal because the denominator has a factor as ...........

  1. $0$

  2. $1$

  3. $2$

  4. $6$


Correct Option: C
Explanation:

If the prime factors in the denominator of a fraction has factors of $2$ and $5$, then the decimals terminate. The denominator has $2$ as a factor.
Therefore, $C$ is the correct answer.


$\dfrac {17}{8}$ can be expressed as $.....$. It is a $........$ decimal.
  1. $ 2.125$, terminating

  2. $ 2.321321...$, non-terminating

  3. $1.125125124...$, recurring

  4. $2.125$, irrational


Correct Option: A
Explanation:

$\dfrac {17}{8}=\dfrac{17\times125}{8\times 125}=  \dfrac{2125}{1000}=2.125$

When the division process does not end and the remainder is not equal to zero; then such decimal is known as ............... decimal

  1. terminating

  2. non-terminating

  3. recurring

  4. irrational


Correct Option: B
Explanation:

The division is completed when we get the remainder zero. In this division process we do not get a zero and it is never ending. This process of division is called a non- terminating decimal.
Therefore, $B$ is the correct answer.

Which of the following fractions will terminate when expressed as a decimal? (Choose all that apply.)

  1. $\frac{1}{256}$

  2. $\frac{27}{100}$

  3. $\frac{100}{27}$

  4. $\frac{231}{660}$

  5. $\frac{7}{105}$


Correct Option: A,B,D
Explanation:

Recall that in order for the decimal version of a fraction to terminate, the fraction's denominator in fully reduced form must have a prime factorization that consists of only 2's and/or 5's. 

The denominator in (A) is composed of only 2's $(256 = 2^8)$. 
The denominator in (B) is composed of only 2's and 5's $(100=2^2\times 5^2)$. 
In fully reduced form, the fraction in (D) is equal to $\frac{7}{20}$ and 20 is composed of only 2's and 5's $(20=2^2\times 5)$.
 By contrast, the denominator in (C) has prime factors other than Z's and 5's $(27 =3^3)$, and in fully reduced form, the fraction in (E) is equal to $\frac{1}{15}$, and 15 has a prime factor other than 2's and 5's $(15 = 3 \times 5)$.

Identify a non-terminating repeating decimal.

  1. $\dfrac{24}{1600}$

  2. $\dfrac{171}{800}$

  3. $\dfrac{123}{2^2 \times 5^3}$

  4. $\dfrac{145}{2^3 \times 5^2 \times 7^2}$


Correct Option: D
Explanation:

An fraction will be terminating decimal only if denominator will be in form of 

${2}^{m}\times{{5}^{n}}$. 
Now lets check denominator of each option 
Only option D does not satisfies this condition So it will be non terminating 
So correct answer will be option D

A rational number can be expressed as a terminating decimal if the denominator has factors _________.

  1. $2$ or $5$

  2. $2$, $3$ or $5$

  3. $3$ or $5$

  4. Only $2$ and $3$


Correct Option: A
Explanation:

Any rational number its denominator is in the form of ${ 2 }^{ m }\times { 5 }^{ n }$,where m,n are positive integer s are terminating decimals.

So correct answer will be option A

Which one of the following has a terminating decimal expansion?

  1. $\displaystyle\frac{5}{32}$

  2. $\displaystyle\frac{7}{9}$

  3. $\displaystyle\frac{8}{15}$

  4. $\displaystyle\frac{1}{12}$


Correct Option: A
Explanation:

We know that a terminating decimal is a decimal that ends. It's a decimal with a finite number of digits. For example $\dfrac {1}{4}=0.25$, it has only two decimal digits.


Now consider the fraction $\dfrac {5}{32}$ whose decimal form will be:

$\dfrac {5}{32}=0.15625$

The resulting decimal number ends with five decimal digits and therefore, it is terminating decimal.

Hence, $\dfrac {5}{32}$ has a terminating decimal expansion.

Which of the following numbers has the terminal decimal representation?

  1. $\dfrac{1}{7}$

  2. $\dfrac{1}{3}$

  3. $\dfrac{3}{5}$

  4. $\dfrac{17}{3}$


Correct Option: C
Explanation:
Option A: $\dfrac {1}{7}=0.1428..$
Option B: $\dfrac {1}{3}=0.3333....$
Option C: $\dfrac{3}{5}=0.6\Rightarrow $ terminal decimal number
Lets check option D : $\dfrac {17}{3}=5.6666...$
Hence, option C is correct.

A real number $\displaystyle \frac{2^2 \times 3^2 \times 7^2}{2^5 \times 5^3 \times 3^2 \times 7}$ will have _________.

  1. Terminating decimal

  2. Non-terminating decimal

  3. Non-terminating and non-repeating decimal

  4. Terminating repeating decimal


Correct Option: A
Explanation:

$\dfrac{2^{2}\times3^{2}\times7^{2}}{2^{5}\times5^{3}\times3^{2}\times7} = 2^{2-5}\times3^{2-2}\times5^{-3}\times7^{2-1}$


                                 $= \dfrac{7}{2^{3}\times5^{3}}$

                                 $= \dfrac{7}{1000}$

                                 $= 0.007$
$0.007$ is a terminating non-repeating decimal

State the following statement is True or False

$\dfrac{987}{10500}$ will have terminating decimal expansion. 

  1. True

  2. False


Correct Option: A
Explanation:

Terminating decimal expansion, because

$ \dfrac{987}{10500}=\dfrac{329}{3500}=\dfrac{329}{2^2.5^3.7}=\dfrac{47}{2^2.5^3}=.094. $

Given that $\dfrac {1}{7} = 0.\overline {142857}$, which is a repeating decimal having six different digits. If $x$ is the sum of such first three positive integers $n$ such that $\dfrac {1}{n} = 0.\overline {abcdef}$, where $a, b, c, d, e$ and $f$ are different digits, then the value of $x$ is

  1. $20$

  2. $21$

  3. $41$

  4. $42$


Correct Option: C
Explanation:

$1^{st}$ number
$x _{1} = 7$
$\Rightarrow \dfrac {1}{x _{1}} = 0.\overline {142857}$
such that,
$2^{nd}$ number
$x _{2} = 13$
$\Rightarrow \dfrac {1}{x _{2}} = 0.\overline {076923}$
$x _{3} = 21$
$\Rightarrow \dfrac {1}{x _{3}} = \dfrac {1}{21} = 0.\overline {047619}$
$x = x _{1} + x _{2} + x _{3}$
$\Rightarrow 7 + 13 + 21 = 41$.

If $x =\dfrac{p}{q}$  be a rational number such that the prime factorization of $q$ is not of the form $2^n 5^m$, where $n, m$ are non-negative integers. Then $x$ has a decimal expansion which is terminating.

  1. True

  2. False

  3. Neither

  4. Either


Correct Option: B
Explanation:

If q is not of the form $2^n*5^m$ then definitely q can take any of the values 3,6,9,12,15,...etc.
As we know 4/3,20/6 all are non-terminating, thus required decimal expansion is non terminating.

The numbers 7.478478.... and 1.101001000100001.....are

  1. Rational and irrational respectively

  2. Both rationals

  3. Both irrationals

  4. None of these


Correct Option: A
Explanation:

In 7.478478.......  we can see that after decimal the digits 478 are repeating itself again and again.

Hence it is a non-terminating and repeating decimal. Therefore it is a rational number.

In 1.101001000100001........  it is a non-terminating and non-repeating decimal.
Therefore it is an irrational number.
Hence option A is correct. 

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