Solutions by everydaycalculation.com

The GCF of 21 and 18 is 3.

- Find the prime factorization of 21

21 = 3 × 7 - Find the prime factorization of 18

18 = 2 × 3 × 3 - To find the GCF, multiply all the prime factors common to both numbers:

Therefore, GCF = 3

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Find hcf of: 42 & 36 63 & 54 7 & 6 105 & 90 147 & 126 42 & 18 21 & 36 63 & 18 21 & 54 105 & 18 21 & 90 147 & 18 21 & 126

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The greatest common factor (GCF) is also known as greatest common divisor (GCD) or highest common factor (HCF).

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