GCF (HCF) of 28 and 40

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Greatest Common Factor of
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What is the Greatest Common Divisor of 28 and 40?

Answer

GCF (HCF) of 28 and 40 is
4

Common factors: 1, 2, 4

4 divides both: 28 ÷ 4 = 7, 40 ÷ 4 = 10 — and 7 and 10 share no factor but 1, so no larger number divides both.

28 = 22 × 7

40 = 23 × 5

Prime2840Lowest power
2222322
5—5—
77——

— = power 0: the prime is not a factor of this number, so it cannot be in the GCF.

GCF = 22 = 4

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GCF Table

Number 1Number 2GCF
28302
28311
28324
28342
28357
28364
28371
28382
28391
28404
284214
28431
28444
28451
28462
28484
28497
28502
28511
28531
28551
285628
28604
28637
28644
287014
28724
28804
288428
289814

FAQ

What is the Greatest Common Divisor of 28 and 40?

GCF (HCF) of 28 and 40 is 4

How to find the GCF of 28 and 40?

You can find the GCF of 28 and 40 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 28 and 40 is 4.

What prime factors do 28 and 40 share?

The prime factorizations of 28 and 40 have 2 × 2 in common, and multiplying those shared primes gives 4 — exactly the greatest common factor.

How does the GCF reduce the fraction 28/40?

Divide the numerator and the denominator by the GCF 4: 28 ÷ 4 = 7 and 40 ÷ 4 = 10. So 28/40 in lowest terms is 7/10.

See Also