I suspect you are talking about integers here, though you don't say so. These situations are called Pythagorean Triplets (In a triangle with 1 right-angle, the sum of the squares of the smaller sides equals the square of the longer side). The smallest (apart from 0,0 and 0) is 52 = 42 + 32. If you are not talking about integers then there is no limit on smallness (apart from 0,0,0).
25 (32 + 42 = 52)
25= 5*5 = (3*3)+(4*4)
16
16
12
25 (32 + 42 = 52)
25= 5*5 = (3*3)+(4*4)
Oh, dude, you're hitting me with some math riddles now? Alright, so the smallest square number that is the sum of two square numbers is 5, because 5 = 1^2 + 2^2. It's like a math puzzle for people who actually enjoy math, you know?
5
10^2 = 6^2 + 8^2 ie 100 = 36 + 64
16
16
The smallest two digit number is 00 (a number used as a wire gauge) and the biggest is 99, so the sum of the biggest and smallest 2-digits numbers is 99 (99 + 00).
12
1+2=3
49
The smallest two-digit composite number is 10, which is the product of 2 and 5. The largest two-digit composite number is 99, which is the product of 3 and 33. To find the sum of the smallest and largest two-digit composite numbers, we add 10 and 99, resulting in 109.