Solution: To find the GCF of 42 and 63, factor both numbers. $42 = 2 \times 3 \times 7$ and $63 = 3^2 \times 7$. The common prime factors are $3$ and $7$. Multiply them: $3 \times 7 = 21$. $\boxed{21}$

Thu, 16 Apr 2026 15:58:58 +0000

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