7 multiple of a two digit number is a perfect square. What will be the Sum of all such possible two digit numbers?

Question

A five-digit number is formed using digits 1,3,5,8 and 9 without repeating any one of them.
What is the sum of all such possible numbers?

Answer 1

It would be 91
As 14^2=196 so two digit will be 28 *7
As 21^2=441 so two digit will be 63*7
So sum of digits=28+63=91

Answer 2

1st) 7 * 28 = 196 = 14*14
2nd) 7*63 = 441 = 21*21

28+63=91

Answer is 91