An elephant makes a pattern of footprints in a straight line. The first row has 2 footprints, the second row has 3, the third has 4, and this continues until the 10th row. How many footprints are there in total?

Step-by-step solution

1. Step 1: Recognise the pattern as an arithmetic sequence: 2, 3, 4, …, 11.
2. Step 2: Number of terms $n=10$ (from row 1 to row 10).
3. Step 3: First term $a=2$, last term $l=11$ (since 2 + (10-1) = 11).
4. Step 4: Use sum formula $S=\frac{n}{2}(a+l)$ for an arithmetic series.
5. Step 5: Compute $S=\frac{10}{2}(2+11)=5\times 13=65$.
6. Step 6: State the total number of footprints.

Concept tested: Sum of arithmetic sequence

Published 1 October 2026 · How this solution was prepared and checked