GCF for 45, 81 and 99

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What's the Greatest Common Factor (GCF) of 45, 81 and 99?

Answer

GCF of 45, 81 and 99 is
9

Common factors: 1, 3, 9

9 divides all three: 45 ÷ 9 = 5, 81 ÷ 9 = 9, 99 ÷ 9 = 11 — and 5, 9 and 11 have no factor but 1 common to all of them, so no larger number divides all three.

45 = 32 × 5

81 = 34

99 = 32 × 11

Prime458199Lowest power
332343232
55———
11——11—

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

GCF = 32 = 9

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GCF Table

1st2nd3rdGCF
4581843
4581851
4581861
4581873
4581881
4581891
4581909
4581911
4581921
4581933
4581941
4581951
4581963
4581971
4581981
4581999
45811001
45811011
45811023
45811031
45811041
45811053
45811061
45811071
45811089
45811091
45811101
45811113
45811121
45811131

FAQ

What's the Greatest Common Factor (GCF) of 45, 81 and 99?

GCF of 45, 81 and 99 is 9

What prime factors do 45, 81 and 99 share?

All three factorizations contain 3 × 3, and multiplying those shared primes gives 9 — exactly the greatest common factor.

Can you get the GCF of 45, 81 and 99 two numbers at a time?

Yes. The GCF of 45 and 81 is 9, and the GCF of 9 and 99 is 9 — the same answer, because the greatest common factor is associative and does not depend on the order of the three numbers.

How does the GCF simplify the ratio 45 : 81 : 99?

Divide every term by the GCF 9: 45 ÷ 9 = 5, 81 ÷ 9 = 9 and 99 ÷ 9 = 11. So 45 : 81 : 99 in lowest terms is 5 : 9 : 11, and no whole number other than 1 divides all three of those.

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