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Here is the problem: Find the greatest common factor of 36, 48, 72.

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Find the greatest common factor (also called GCD or HCF) of the numbers.

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Prime factorization of each number.

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Euclidean algorithm for GCF(36, 48). 48 equals 1 times 36 plus 12; 36 equals 3 times 12 plus 0.

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The last non-zero remainder is the GCF.

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Euclidean algorithm for GCF(12, 72). 72 equals 6 times 12 plus 0.

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The last non-zero remainder is the GCF.

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Confirm with shared prime factors. Multiply the primes common to every number, each with its smallest exponent.

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So the answer is 12.

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12 is the largest whole number that divides every number exactly.

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36 divided by 12 equals 3.

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48 divided by 12 equals 4.

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72 divided by 12 equals 6.