九是一个平方数。

Nine is a square number.

对于每个整数，都是完全平方数。

For all integers , is a perfect square.

下一个目标数字是10。你无法通过加法直接得到这个数字，因此你还是要先得到某个完全平方数。

Now to 10. You can't get straight there through addition alone, so you're going to have to reach another square.

看上去是随机的，但是你需要避开10，14和完全平方数，毕竟你之后还要用到它们。

It's somewhat arbitrary, but you know that you want to avoid 10, 14, and perfect squares, since you'll need them later.