Find the greatest common factor of 2 or 3 integers.

Problem

Find the greatest common factor of 7, comma, 15, comma and 21.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, p, i or 2, slash, 3, space, p, i
Get first 4 correct, or 5 in a row.