This solution was submitted by Sarah Gray from Archbishop Sancroft High School:
The numbers were -1,1,3,5,10
| -1 + 1 = 0 | 3 + (-1) = 2 | 3 + 1 = 4 | 5 + (-1) = 4 |
| 5 + 1 = 6 | 5 + 3 = 8 | 10 + (-1) = 9 | 10 + 1 = 11 |
| 10 + 3 = 13 | 10 + 5 = 15 |
Correct solutions were also received from:
.| Rachel Cook | West Flegg Middle School |
| Luke Blackwell and Ian Morris | No school given. |
| Wymondham High School |