Hello Aspirant!

No, In my calculation 3 natural number's squares can't give you total of 100,

Instead 2 natural number's squares can give you and it's be 8 and 6

As, 8's square is 64 & 6's square is 36

8^2 + 6^2 = 64 + 36 = 100,

So the small natural number will be 6 for square of two natural numbers which sum is 100.

Ask if any future query...

Good Luck!