complete row. Count that row before moving your eyes downward. The first row contains two balls. The next contains five. Keeping those groups separate makes it easier to see that the pattern alternates rather than forming one continuous block.
The middle row contains two balls, followed by another row of five and a final row of two. Written as a sum, the arrangement is 2 + 5 + 2 + 5 + 2. You can check the same result by combining the two longer rows first: five plus five gives ten. The three shorter
