GCF of 14 and 21

Find the Greatest Common Factor (GCF) of 14 and 21 with a complete step-by-step solution. The GCF is the largest number that divides both numbers without leaving a remainder.

GCF of and
Answer: GCF(14, 21) = 7
Step-by-Step Solution
Step 1 Find the Factors of 14

To find the GCF of 14 and 21, we first need to find all factors of each number.

The factors of 14 are numbers that divide 14 evenly:


1 × 14 = 14, 2 × 7 = 14

Factors of 14: 1, 2, 7, 14

Step 2 Find the Factors of 21

Now we find all factors of 21:


1 × 21 = 21, 3 × 7 = 21

Factors of 21: 1, 3, 7, 21

Step 3 Find the Common Factors

The common factors are numbers that appear in both lists:


Factors of 14: 1, 2, 7, 14

Factors of 21: 1, 3, 7, 21


Common factors: 1, 7


The Greatest Common Factor is the largest of these: 7

Step 4 Prime Factorization Method

We can also find the GCF using prime factorization:


14 = 2 × 7
21 = 3 × 7

Take the common prime factors with the lowest powers:

GCF = 7 = 7
Step 5 Euclidean Algorithm

The Euclidean algorithm is a fast way to find the GCF using repeated division:


21 = 1 × 14 + 7
14 = 2 × 7 + 0

When the remainder is 0, the GCF is the last divisor: 7

Step 6 Final Answer

GCF(14, 21) = 7