www.reference.com/world-view/friendly-numbers-math-69926feee0de7b7f

Friendly numbers are individual numbers that make up part of what is known as a friendly pair. Friendly numbers always come in sets of two, and they are known for having a positive density.

www.reference.com/world-view/number-model-math-4919107bd2f566de

A number model in math is a sentence that illustrates how the parts of a number story are related. The equation may include addition, subtraction, division and multiplication and may be expressed as words or in number form.

www.reference.com/article/mean-math-7d369cbf28a3ab35

In math, the mean is the average of a set of numbers. To determine the mean, add all numbers in a set and take this answer and divide it by how many numbers are in the set.

www.reference.com/article/think-through-math-b63e5148ea6dded0

Think Through Math is an adaptive math instruction website for students third grade and above. It features math lessons taught individually by real teachers to students.

www.reference.com/world-view/area-math-2156c3c41f57792b

In mathematics, area is defined as the amount of two-dimensional space occupied by a shape. It can be calculated by multiplying two lengths of the shape, such as the length and width of a rectangle. The units of area are always unit of length squared.

www.reference.com/world-view/basic-fact-math-50ac9d08378fad2

A "basic fact" in math is defined as any mathematical number, fact or idea instantly recalled without resorting to strategies, according to NZCER.org. The main basic facts encountered in math are "whole-number" basic facts, in particular multiplication, addition, division and subtraction.

www.reference.com/article/fun-math-games-cool-math-2b2e9a567f333bbc

A couple of fun games on Coolmath-Games.com include "Pixel Quest" and "Flip Dojo." Both games require players to solve math puzzles and avoid obstacles to advance to higher levels.

www.reference.com/article/cool-math-games-6a84ffbaae481267

A cool math game that is available online is "2048" and is offered as a mobile application. Cool Math 4 Kids offers math games geared toward children, including "The Timernator" and "Arithmetic Game."

www.reference.com/article/prime-number-math-adc2c131e08371c7

A prime number in math is an integer greater than 1 that is evenly divisible by only 1 and the number itself. One is not considered a prime number, because prime numbers by definition have two factors, and the number 1 only has one factor: 1.

www.reference.com/world-view/prime-numbers-important-math-f9c17c6f7bf7e3e2

Prime numbers are important in mathematics because they function as indivisible units and serve as the foundation of several mathematical disciplines. Because a prime number is a natural number greater than 1 that can only be divided by itself and 1, all non-prime numbers, which are called composite