Question

What is the greatest common factor of 63 and 21

Answer 1

Factors of 21={1,3,7,21}

Factors of 63={1,3,7,9,21,63}

the highest common factor (HCF) is 21.

Answer 2

Answer: 21

Step-by-step explanation: To find the greatest common factor for the numbers 21 and 63, make a factor tree for each of the numbers.

21 is 3 × 7.

63 is 3 × 21 and 21 is 3 × 7.

The greatest common factor therefore is 3 × 7 or 21.