Chapter 3.2, Problem 9MS

Six times as much $\left(E\times H\right).$ If we let N stand for the set of all natural numbers, then we write 6N for the set of natural numbers all multiplied by 6 $\left(\text{so 6N = }\left\{\text{6, 12, 18,24,}\mathrm{...}\right\}\right)\text{.}$ Show that the sets N and 6N have the same cardinality by describing an explicit one-to-one correspondence between the two sets.