Solutions by everydaycalculation.com

The GCF of 21 and 11 is 1.

- Find the prime factorization of 21

21 = 3 × 7 - Find the prime factorization of 11

11 = 11 - To find the GCF, multiply all the prime factors common to both numbers:

Therefore, GCF = 1

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Find hcf of: 42 & 22 63 & 33 105 & 55 147 & 77 42 & 11 21 & 22 63 & 11 21 & 33 105 & 11 21 & 55 147 & 11 21 & 77

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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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