Learn how rounding numbers works for decimals, sums, and significant figures. Get the rules and examples for various quantities. Rounding Numbers Rules and Examples This entry was posted on April 24, 2022 by Anne Helmenstine (updated on April 28, 2022)

Learn about the Pythagorean theorem in geometry. Get its definition, formula, and worked example math problems. Pythagorean Theorem – Definition, Formula, Problems This entry was posted on December 26, 2021 by Anne Helmenstine (updated on January 3, 2022)

Learn about the number zero. Get the definition and interesting zero facts and learn about its history and role in math. Number Zero Definition and Facts This entry was posted on December 19, 2021 by Anne Helmenstine (updated on December 20, 2021)

Learn how to calculate a tip without a calculator easily in your head. See examples and know how much to tip for different services. How to Calculate a Tip Without a Calculator This entry was posted on December 9, 2021 by Anne Helmenstine (updated on December 12, 2021)

Learn what an exact number is in chemistry, physics, and math. Get the definition and examples of exact numbers. What Is an Exact Number? Definition and Examples This entry was posted on September 19, 2021 by Anne Helmenstine (updated on December 19, 2021)

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 This entry was posted on August 28, 2021 by Anne Helmenstine (updated on August 30, 2021)

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 This entry was posted on July 10, 2021 by Anne Helmenstine (updated on December 19, 2021)

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 ... This entry was posted on June 30, 2021 by Anne Helmenstine (updated on February 12, 2022)

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 This entry was posted on June 24, 2021 by Anne Helmenstine (updated on December 19, 2021)