With the sum of 99, we will get 50 pairs whole numbers. Why?
Let’s start with
0+ 99
1 + 98
2 + 97
3 + 96
4 + 95
5 + 94
6 + 93
7 + 92
8 + 91
9 + 90
10 + 89
………
……..
43 + 49
44 + 50
Therefore, if you’re going to count all pairs of the whole number, you will get 50 pairs of the whole number with the sum of 99.