GCF of 28 and 70 (Greatest Common Factor)

"Greatest Common Factor" Calculator
Greatest Common Factor of
and

What is the Greatest Common Divisor of 28 and 70?

Answer

GCF of 28 and 70 is
14

(Fourteen)

Finding GCF for 28 and 70 using all factors (divisors) listing

The first method to find GCF for numbers 28 and 70 is to list all factors for both numbers and pick the highest common one:

All factors of 28: 1, 2, 4, 7, 14, 28

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

So the Greatest Common Factor for 28 and 70 is 14

Finding GCF for 28 and 70 by Prime Factorization

The second method to find GCF for numbers 28 and 70 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 28: 2, 2, 7

All Prime Factors of 70: 2, 5, 7

As we can see there are Prime Factors common to both numbers: 2, 7

Now we need to multiply them to find GCF: 2 × 7 = 14

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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 28 and 70? (The answer is: 14). Select the first number (e.g. '28') and the second number (e.g. '70'). 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
28324
28331
28342
28357
28364
28371
28382
28391
28404
284214
28431
28444
28451
28462
28471
28484
28497
28502
28511
28531
28551
285628
28604
28637
28644
287014
28724
288428
289814
281057

FAQ

What is the Greatest Common Divisor of 28 and 70?

GCF of 28 and 70 is 14

How to find the GCF of 28 and 70?

You can find the GCF of 28 and 70 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 28 and 70 is 14.

What prime factors do 28 and 70 share?

The prime factorizations of 28 and 70 have 2 × 7 in common, and multiplying those shared primes gives 14 — exactly the greatest common factor.

How does the GCF reduce the fraction 28/70?

Divide the numerator and the denominator by the GCF 14: 28 ÷ 14 = 2 and 70 ÷ 14 = 5. So 28/70 in lowest terms is 2/5.

See Also