Question

state number of numbers between;

4^2 and 5^2
15^2 and 16^2
10^2 and 11^2
30^2 and 31^2

Answer 1

Simply add 4&5 to get the difference between their squares:-
=4+5=9
and then subtract 1 to get the number of numbers between them: -
=9-1=8
And the numbers are 17,18,19,20,21,22,23&24

In the same manner
15+16=31
31-1=30

10+11=21
21-1=20

30+31=61
61-1=60