The Greatest Common Divisor of 63 and 84 is as follows:
21
To find the Greatest Common Divisor of 63 and 84, we first list all the divisors of 63
and all the divisors of 84. Then, we compare the two lists of divisors and pick the largest (greatest)
number that is on both lists, which will be the Greatest Common Divisor of 63 and 84.
Here is the list of 63 divisors: 1, 3, 7, 9, 21, 63
And here is the list of 84 divisors: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
When we compare the two lists, we see that the greatest number they have in common is 21.
Therefore, once again, the answer to the question "What is the Greatest Common Divisor of 63 and 84?" is:
21
Note, the divisors of 63 are all the numbers you can divide into 63 with no remainder, and the divisors of 84 are
all the numbers you can divide into 84 with no remainder.

