- Greatest Common Divisor is the largest positive integer that divides two or more numbers without remainder
- Greatest Common Divisor (GCD) is also known as Greatest Common Factor (GCF) and Highest Common Factor (HCF)
- GCD is mainly useful for reducing fractions to be in lowest terms possible.
For example, let's take a fraction of 4/6 (four sixth). The counter is 4, and the denominator is 6. GCD of the numbers 4 and 6 is 2, so divide the numerator and the fraction by 2 - we get 2/3 (two thirds), which is the simplest form of this fraction.