Solving this ball problem is very simple. A very simple method can be used for this. These balls are available in 4 layers. Therefore, the problem can be solved very simply by calculating layers. The number of balls per layer can be shown as follows.
1st layer: 1
2nd layer: 2 × 2 = 4
3rd layer: 3 × 3 = 9
4th layer: 4 × 4 = 16
Accordingly, total ball count is 1 + 4 + 4 + 9 + 16 = 30 balls.
