GCF of 70 and 21 (Greatest Common Factor)

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest Common Divisor of 70 and 21?

Answer

GCF of 70 and 21 is
7

(Seven)

Finding GCF for 70 and 21 using all factors (divisors) listing

The first method to find GCF for numbers 70 and 21 is to list all factors for both numbers and pick the highest common one:

All factors of 70: 1, 2, 5, 7, 10, 14, 35, 70

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

So the Greatest Common Factor for 70 and 21 is 7

Finding GCF for 70 and 21 by Prime Factorization

The second method to find GCF for numbers 70 and 21 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 70: 2, 5, 7

All Prime Factors of 21: 3, 7

As we can see there is only one Prime Factor common to both numbers. It is 7

So 7 is the Greatest Common Factor of 70 and 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 70 and 21? (The answer is: 7). Select the first number (e.g. '70') 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
70217
7010010
7010535
7011010
701255
7013010
701355
7015010
7016010
701655
7017010
7017535
7018010
701855
702055
702155
7022010
702255
7023010
702355
7024535
7025010
702555
7026010
7027010
7028070
7029010
7030010
703055
7031010

FAQ

What is the Greatest Common Divisor of 70 and 21?

GCF of 70 and 21 is 7

How to find the GCF of 70 and 21?

You can find the GCF of 70 and 21 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 70 and 21 is 7.

What prime factors do 70 and 21 share?

The prime factorizations of 70 and 21 have 7 in common, and multiplying those shared primes gives 7 — exactly the greatest common factor.

How does the GCF reduce the fraction 70/21?

Divide the numerator and the denominator by the GCF 7: 70 ÷ 7 = 10 and 21 ÷ 7 = 3. So 70/21 in lowest terms is 10/3.

See Also