Learn what an exact number is in chemistry, physics, and math. Get the definition and examples of exact numbers.

# Mathematics

Learn how to convert degrees to radians and back again. This is a key angle conversion in geometry and trig.

## How to Convert Degrees to Radians – Angle Conversion

Learn what the absolute value or modulus of a number is in math. Get examples and see how to solve absolute value equations.

## What Is Absolute Value? Definition and Examples

Learn what a prime number is and see how to tell if a number is prime. Get a list of primes under 100 and 1000.

## What Is a Prime Number? How to Tell If a ...

Learn what a real number is in math. Get examples of numbers that are real versus those that are imaginary.

## What Is a Real Number? Definition and Examples

Learn what infinity is in math. Get interesting infinity facts and examples. Learn the properties of this "number".

## What Is Infinity? Infinity Facts and Examples

Learn how to calculate percentage increase or decrease. See examples of percentage change and how to interpret them.

## How to Calculate Percentage Increase or Decrease (Percentage Change)

Learn about equivalent equations in algebra. See how to recognize and solve them and learn the rules for writing them.

## Equivalent Equations in Algebra

Get interesting circle facts. See how to find the area, circumference, diameter, and radius of a circle in geometry.