8
64=2**6 2*6=12
Well, 1 is equal to 1. 9 is equal to 9. So any number from 0 to 9. I do not think this is what is meant by the question. If you mean any number with more than one digit. There is no such number. Because 11 sums to 2. 19 sums to 10. 21 sums to 3. 29 sums to 11. 111 sums 3. 119 sums to 11. The sums do not grow as fast the increase of digits.
7X8=56
360
Neither; the sums are equal.
You should use your calculator for such simple sums. It is far quicker and involves fewer key depressions. I could tell you that the answer is 51 but how can you be sure that I did not make a mistake? Or that I am not messing about?
900
An infinite number.
Yes
64
10