The Greeks, particularly Archimedes, made significant contributions to the study of pi (π) and its approximation.

Pythagoras is credited with discovering the Pythagorean theorem, which bears his name.

Plato is known for his contributions to geometry, including the study of the five regular solids (Platonic solids).

The ancient Babylonians used a sexagesimal (base-60) number system, which is still used today for measuring time and angles.

The Rhind Mathematical Papyrus is an ancient Egyptian mathematical text that contains problems and solutions related to geometry, algebra, and arithmetic.

The ancient Greeks developed a method for constructing regular polygons using a compass and straightedge, known as compass-and-straightedge construction.

Eratosthenes is known for his contributions to number theory, including the development of the sieve of Eratosthenes, a method for finding prime numbers.

The ancient Chinese developed a mathematical tool known as the abacus, which is used for performing arithmetic calculations.

Zeno of Elea is credited with developing the concept of infinity and the idea of a mathematical proof.

The ancient Mayans developed a sophisticated system of mathematics that included the concept of place value.

Apollonius of Perga is known for his contributions to the study of conic sections, including the development of the parabola, ellipse, and hyperbola.

The ancient Indians developed a system of mathematics that included the concept of zero.

Hipparchus is known for his contributions to the study of trigonometry, including the development of trigonometric tables.

The ancient Egyptians used geometry to design and construct pyramids, temples, canals, and other structures.

Pascal is known for his contributions to the study of probability, including the development of the concept of expected value.