In the sequence 2, 7, 15, 26, ___, what is the next number?

Step-by-step solution

1. Find the differences: $7-2=5$, $15-7=8$, $26-15=11$.
2. These differences increase by $3$ each step: $5,8,11$.
3. The next difference is $11+3=14$.
4. Add this to the last term: $26+14=40$.
5. Hence the next number is $40$.

Concept tested: Sequence with increasing differences

Published 7 October 2026 · How this solution was prepared and checked