Tag: rounding off decimals

Questions Related to rounding off decimals

Write the number of significant digits in:

$3.005$.

  1. $4$

  2. $2$

  3. $1$

  4. $0$


Correct Option: A
Explanation:

Zeroes placed between other digits are always significant.
$\therefore  3.005$ has $4$ significant digits.

Write the number of significant digits in:

$5.16 \times 10^8$.

  1. $3$

  2. $1$

  3. $2$

  4. $9$


Correct Option: A
Explanation:

$5.16\times 10^8$
There are $3$ significant figures. When a number is  written in scientific notation, only significant figures are placed into the numerical portion.


Write the number of significant digits in:

$16.000$.

  1. $2$

  2. $5$

  3. $16$

  4. $1$


Correct Option: B
Explanation:

All zeroes which are both to the right of the decimal point and to the right of all non-zero significant digits are themselves significant.
$\therefore  16.000$ has $5$
significant digits

Write the number of significant digits in $23.4$

  1. $2$

  2. $23.4$

  3. $3$

  4. $1$


Correct Option: C
Explanation:

Non-zero digits are always significant.

$\therefore  23.4$ has $3$
significant digits.

Divide $7$  by $11$ and express the result in two significant digits.

  1. $0.64$

  2. $0.583$

  3. $0.54$

  4. $0.67$


Correct Option: A
Explanation:

On dividing 7 by 11, we get 0.6363636363.... .

If we have to express this in two significant digits, then it would be 0.64 as 6 is > 5  and 1 would get added to 3.

Write the number of significant digits in:

$0.07$.

  1. $7$

  2. $1$

  3. $3$

  4. $2$


Correct Option: B
Explanation:

Zeroes placed before other digits are not significant.
$\therefore  0.07$
has $1$ significant digit.

Write the number of significant digits in:

$0.0016$.

  1. $2$

  2. $5$

  3. $1$

  4. $4$


Correct Option: A
Explanation:

Zeroes placed before other digits are not significant.
$\therefore  0.0016$  has $2$ significant digits.

Write the number of significant digits in:

$805.060$.

  1. $3$

  2. $2$

  3. $5$

  4. $6$


Correct Option: D
Explanation:

All zeroes which  are both to the right of the decimal point and to the right of all non-zero significant digits  are themselves significant.
$\therefore  805.060$ has $6$
significant digits

For rational numbers, $x$ and $y,$ if $x > y,$ then which of the following is always a positive rational number?

  1. $ y - xy$

  2. $ xy-x$

  3. $ y-x$

  4. $ x- y $


Correct Option: D
Explanation:
If $x>y$

$y-xy\rightarrow $ can be both positive and negative.

Example coside $x>1$ & $y>0$

$\left(y-xy\right)<0$

$xy-x\rightarrow $ can be both positive and negative 

$y-x\rightarrow $ always negative

$\boxed {x-y\rightarrow always\ positive\ since\ x>y}$

$0.\overline{5}$ in the form of $\frac{p}{q}$ is :

  1. $\dfrac{9}{5}$

  2. $\dfrac{5}{10}$

  3. $\dfrac{5}{9}$

  4. $\dfrac{10}{5}$


Correct Option: C
Explanation:

$Let\quad x=.555....\ On\quad multiplying\quad by\quad 10\quad on\quad both\quad sides\quad \ 10x=5.555....\ On\quad subtracting\quad both\quad equations\quad \ 9x=5\ x=\dfrac { 5 }{ 9 } \ $

Hence, correct answer is option C.