GCF (HCF) of 63 and 42

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What is the Greatest Common Divisor of 63 and 42?

Answer

GCF (HCF) of 63 and 42 is
21

Common factors: 1, 3, 7, 21

21 divides both: 63 ÷ 21 = 3, 42 ÷ 21 = 2 — and 3 and 2 share no factor but 1, so no larger number divides both.

63 = 32 × 7

42 = 2 × 3 × 7

Prime6342Lowest power
2—2—
33233
7777

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

GCF = 3 × 7 = 21

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GCF Table

Number 1Number 2GCF
63279
63287
63291
63303
63311
63321
63333
63341
63357
63369
63371
63381
63393
63401
63411
634221
63431
63441
63459
63461
63471
63483
63497
63501
63513
63521
63531
63549
63551
63567

FAQ

What is the Greatest Common Divisor of 63 and 42?

GCF (HCF) of 63 and 42 is 21

How to find the GCF of 63 and 42?

You can find the GCF of 63 and 42 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 63 and 42 is 21.

What prime factors do 63 and 42 share?

The prime factorizations of 63 and 42 have 3 × 7 in common, and multiplying those shared primes gives 21 — exactly the greatest common factor.

How does the GCF reduce the fraction 63/42?

Divide the numerator and the denominator by the GCF 21: 63 ÷ 21 = 3 and 42 ÷ 21 = 2. So 63/42 in lowest terms is 3/2.

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