A multiple of a number is any product of that number with another number. For 6, the first few multiples are 6 × 1, 6 × 2, 6 × 3, 6 × 4, 6 × 5 ... which are 6, 12, 18, 24, 30, and so on. 42 is a multiple of 6, since 6 × 7 = 42. So the answer is C. The
other choices (2, 3, and 1) are factors of 6, not multiples.