GCF of 63 and 21 (Greatest Common Factor)

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest Common Divisor of 63 and 21?

Answer

GCF of 63 and 21 is
21

(Twenty-one)

Finding GCF for 63 and 21 using all factors (divisors) listing

The first method to find GCF for numbers 63 and 21 is to list all factors for both numbers and pick the highest common one:

All factors of 63: 1, 3, 7, 9, 21, 63

All factors of 21: 1, 3, 7, 21

So the Greatest Common Factor for 63 and 21 is 21

Finding GCF for 63 and 21 by Prime Factorization

The second method to find GCF for numbers 63 and 21 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 63: 3, 3, 7

All Prime Factors of 21: 3, 7

As we can see there are Prime Factors common to both numbers: 3, 7

Now we need to multiply them to find GCF: 3 × 7 = 21

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About "Greatest Common Factor" Calculator

This calculator will help you find the greatest common factor (GCF) of two numbers. For example, it can help you find out what is the Greatest Common Divisor of 63 and 21? (The answer is: 21). Select the first number (e.g. '63') and the second number (e.g. '21'). After that hit the 'Calculate' button.
Greatest Common Factor (GCF) also known as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF) - it is the largest positive integer that divides each of the integers with zero remainder.
"Greatest Common Factor" Calculator

Greatest Common Factor of

and

GCF Table

Number 1Number 2GCF
6363
6377
6381
6399
63101
63111
63123
63131
63147
63153
63161
63171
63189
63191
63201
632121
63221
63231
63243
63251
63261
63279
63287
63291
63303
63311
63321
63333
63341
63357

FAQ

What is the Greatest Common Divisor of 63 and 21?

GCF of 63 and 21 is 21

How to find the GCF of 63 and 21?

You can find the GCF of 63 and 21 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 63 and 21 is 21.

What prime factors do 63 and 21 share?

The prime factorizations of 63 and 21 have 3 × 7 in common, and multiplying those shared primes gives 21 — exactly the greatest common factor.

How does the GCF reduce the fraction 63/21?

Divide the numerator and the denominator by the GCF 21: 63 ÷ 21 = 3 and 21 ÷ 21 = 1. So 63/21 in lowest terms is 3/1.

See Also