You already know how to count in 5s.
5 10 15 20 25 30 35 40 45 50
Your answers are actually the 5 times table.
Here is the 5 times table.
Try to learn it by heart.
0 × 5 = 0
1 × 5 = 5
2 × 5 = 10
3 × 5 = 15
4 × 5 = 20
5 × 5 = 25
6 × 5 = 30
7 × 5 = 35
8 × 5 = 40
9 × 5 = 45
10 × 5 = 50