Greatest Common Divisor (GCD) of 4 and 21

The Greatest Common Divisor (GCD) of 4 and 21 is the largest positive integer that divides both 4 and 21. Mathematically, the problem we are solving is:

GCD(4,21)

To solve the problem, we will list all the positive integers (divisors) that can be divided into 4 and 21. We will then compare the lists of divisors to find the greatest divisor they have in common.

Divisors of 4:
1, 2, and 4.

Divisors of 21:
1, 3, 7, and 21.

When we compare the lists of divisors above, we see that the largest number they have in common is 1. Thus, the Greatest Common Divisor (GCD) of 4 and 21 is:

GCD(4,21) = 1

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Greatest Common Divisor (GCD) of 4 and 22
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