Mathematics for IGCSE & O level - Number (Section 1 - No. 13)

Which of the following is a common factor of 18 and 24?

Factors of 18: 1, 2, 3, 6, 9, 18. Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24. 3 is a factor of both.