Multiple choice Find the H.C.F. of 20 and 30. 2 3 10 20 Reveal answer Fill a bubble to check yourself C Correct answer Explanation Factors of 20 = 1, 2, 4, 5, 10, 20 Factors of 30 = 1, 2, 3, 5, 6, 10, 15, 30 H.C.F. = 10