Educator

Greatest Common Divisor

• Greatest Common Divisor (GCD) is also known as Greatest Common Factor (GCF). The Greatest Common Divisor of two or more numbers is the largest factor shared by all the numbers.
• You can find the GCD by listing factors. If you do this, make sure you put the factors for each number in pairs to avoid omitting a number.
• For example: 12: 1 • 12, 2 • 6, 3 • 4; then put the factors in ascending order 12: 1, 2, 3, 4, 6, 12
• You can find the GCD by using Prime Factorization.
• Steps to Using Prime Factorization to Find GCD:
1. Make the factor tree for each number
2. Circle each factor that the numbers have in common
3. Take only one set of circled factors and multiply
• Check your answer by dividing each answer by the GCD, there should be no remainders