Question

Find the greatest common factor of the numbers.

21, 99

Short answer

The greatest common factor is 3.

Step-by-step solution

Step-1 – Define greatest common factor

A common factor is a whole number that is a factor of two or more nonzero whole numbers. The greatest of the common factors is the greatest common factor (GCF).

Step-3 – Factor the numbers

Factor both the numbers 21 and 99.

The factors of 21 are: $21=7\times 3$

The factors of 99 are: $99=3\times 3\times 11$

Step-3 – State the conclusion

From the factorization it can be observed that 3 is common in both the numbers, therefore, the greatest common factor is 3.