Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 I double a number and get 34. What was it? (number)
Show worked solution
34 ÷ 2 = 17.
2 I add 9 to a number, then double the result, getting 30. What was the number? (number)
Show worked solution
Undo: 30 ÷ 2 = 15; 15 − 9 = 6. Last step first!
3 A string folded once (2 sections) has its middle marked; unfolded, each section is 12 cm. Length? (number, cm)
Show worked solution
2 × 12 = 24 cm.
Level 2 · Core
4 I think of a number, subtract 4, then multiply by 3, getting 27. The number? (number)
Show worked solution
27 ÷ 3 = 9; 9 + 4 = 13. Forward: (13−4)×3 = 27 ✓
5 Ana spent $5 on lunch, then half the rest on a book, leaving $8. How much did she start with? (number, $)
Show worked solution
Before book: 8 × 2 = 16. Before lunch: 16 + 5 = $21.
6 A movie ends at 4:15 pm after running 1 h 50 min. What time did it start?
Show worked solution
4:15 − 1 h = 3:15; − 15 = 3:00; − 35 = 2:25 pm.
Level 3 · Challenge
7 A string is folded in half 3 times and marked at every fold; unfolded, neighbouring marks are 5 cm apart. Length? (number, cm)
Show worked solution
3 folds → 8 sections × 5 cm = 40 cm.
8 Sam gave away half his cards, then bought 10 more, then gave away half again, leaving 12. How many did he start with? (number)
Show worked solution
Undo: 12 × 2 = 24 (before last give); 24 − 10 = 14 (before buying); 14 × 2 = 28. Forward: 28→14→24→12 ✓
9 A bus reached the depot at 6:05 pm after a 40-minute route, a 15-minute break, and a 25-minute route before that. When did the FIRST route begin?
Show worked solution
6:05 − 40 = 5:25; − 15 = 5:10; − 25 = 4:45 pm.