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Find the greatest common factor of 7,15 , and 21 .

Find the greatest common factor of 77,1515 , and 2121 .

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Q. Find the greatest common factor of 77,1515 , and 2121 .
  1. Factors of 77: List the factors of 77.\newline77 is a prime number, so its only factors are 11 and itself.\newlineFactors of 77: 1,71, 7
  2. Factors of 1515: List the factors of 1515.\newline1×15=151 \times 15 = 15\newline3×5=153 \times 5 = 15\newlineFactors of 1515: 11, 33, 55, 1515
  3. Factors of 2121: List the factors of 2121.\newline1×21=211 \times 21 = 21\newline3×7=213 \times 7 = 21\newlineFactors of 2121: 11, 33, 77, 2121
  4. Common factors of 77, 1515, and 2121: Identify the common factors of 77, 1515, and 2121.\newlineFactors of 77: 11, 77\newlineFactors of 1515: 11, 151511, 151522, 1515\newlineFactors of 2121: 11, 151511, 77, 2121\newlineThe only common factor is 11, since it is the only factor that appears in all three lists.
  5. Greatest common factor (GCF) of 77, 1515, and 2121: Determine the greatest common factor (GCF) of 77, 1515, and 2121.\newlineSince the only common factor is 11, the GCF of 77, 1515, and 2121 is 11.

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