1. 72

2. a. 7
b. Scores of 10 and 11 are equally likely
c. 4 and 24

3. 26. (a quick way of approaching this if you know that 676 is a perfect square is to realise that its square root must lie between 20 (20 X 20 = 400) and 30 (30 X 30 = 900). Then, since 676 ends in 6 the only candidates are 24 X 24 and 26 X 26. However, if the answer was 24, then 676 would have 3 as one of its factors; its digits must add up to some multiple of 3. But 6 + 7 + 6 =13. That rules out 24; the answer must be 26)

4. 6, if he saves and reuses the butts from his own newly rolled cigarettes.

5. 3 cats

6. Two. (83 and 89)

7. a. 15 triangles; b. 9 triangles

8. 62 photos

9. a. Yes b. Yes c. Yes (as the gap is 1.6 m some men might have to crouch a bit)

10. The ring road is about 10% quicker