Question

How many of the numbers from 10 through 97 have the sum of their digits equal to a perfect​ square?

Answer 1

Perfect squares are:
1,4,9,16,25,36,49,64,81,100,....

the sum of the digits of our biggest number is 16 so any perfect square bigger than 16 doesn't work for us
1-
1+0=1 so any number containing the digits will work(keep in mind we only will look into whole numbers because digits can't be negative or have fractions or be irrational)
thereful 10 works for our category
2-
0+4=4
1+3=4
2+2=4
22 13 31 and 40 will work two
3-
0+9
1+8
2+7
3+6
4+5
90 18 81 27 72 36 63 45 54
4-
0+16
1+15
2+14
3+13
4+12
5+11
6+10
7+9
8+8
79 97 88

so our set of numbers contain:
10 22 13 31 40 90 18 81 27 72 36 63 45 54 79 97 88