Question

√39 is between which 2 integers?

Answer 1

Think of the squares of the whole numbers.
0^2 = 0
1^2 = 1
2^2 = 4
3^2 = 9
4^2 = 16
5^2 = 25
6^2 = 36
7^2 = 49

39 is between 36 and 49, so sqrt(39) is between 6 and 7.