Is 7 a secret square number?

No.12904500 ViewReplyOriginalReport
I call this one Mr Bev's theorem.

1. You square any rational number,
2. Adds its digit together:
3. If it has more than one digit, repeat 2.
Else, your answer will be a square number (or 7)

So, is 7 a secret square number???

More seriously tho, why does it always end up at 1, 4, 7, 9 and not, 2, 3, 5, 8?