Question: are all multiples of 3 odd?
Answer: The first ten multiples of 3 are listed below: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30. ... On the other hand, an odd number times an odd number is odd so the 1st, 3rd, 5th, \ldots elements of this sequence are odd: since 6 is a multiple of 2, any multiple of 6 is also a multiple of 2 and so must be even.