Question

If the units digit of a number is 0, then tens digit of square of that number is​

Answer 1

If unit digit of a perfect square is 0 then ten's digit has to be 0. E.g. 100,400,900 all are Perfect Square having unit digit 0 and tens digit is 0. – If a number ends with 2, 3, 7 or 8 then it can't be perfect square. 88 we get 7744.