Think of a Number Puzzles Worksheet

Maths tricks trick 6: Think of a number · Set 49 · 40 questions

The trick (Undo the steps): Going forwards: do the steps in order. Going backwards: start from the result and undo each step, last one first. Undo + with −, × with ÷, and doubling with halving.

1. 1.I thought of a number, added 8 and then doubled it. I got 54. What was my number?
2. 2.I thought of a number, multiplied it by 3 and added 4. I got 16. What was my number?
3. 3.Magic trick! Think of 19. Double it, add 8, halve it, then take away 19. What number do you get?
4. 4.Think of 10. Multiply it by 4, then add 3. What number do you end with?
5. 5.Magic trick! Think of 9. Double it, add 8, halve it, then take away 9. What number do you get?
6. 6.Think of 2. Multiply it by 4, then add 4. What number do you end with?
7. 7.Think of 7. Multiply it by 2, then add 6. What number do you end with?
8. 8.Magic trick! Think of 6. Double it, add 8, halve it, then take away 6. What number do you get?
9. 9.I thought of a number, added 5 and then doubled it. I got 16. What was my number?
10. 10.I thought of a number, added 1 and then doubled it. I got 32. What was my number?
11. 11.Think of 4. Multiply it by 4, then add 2. What number do you end with?
12. 12.Think of 15. Multiply it by 2, then add 3. What number do you end with?
13. 13.Think of 9. Multiply it by 4, then add 1. What number do you end with?
14. 14.I thought of a number, added 5 and then doubled it. I got 28. What was my number?
15. 15.I thought of a number, multiplied it by 3 and added 5. I got 35. What was my number?
16. 16.Think of 9. Multiply it by 5, then add 8. What number do you end with?
17. 17.Think of 11. Multiply it by 4, then add 7. What number do you end with?
18. 18.Magic trick! Think of 7. Double it, add 6, halve it, then take away 7. What number do you get?
19. 19.I thought of a number, added 5 and then doubled it. I got 20. What was my number?
20. 20.I thought of a number, multiplied it by 3 and added 7. I got 40. What was my number?
21. 21.Magic trick! Think of 17. Double it, add 8, halve it, then take away 17. What number do you get?
22. 22.Think of 2. Multiply it by 2, then add 2. What number do you end with?
23. 23.I thought of a number, multiplied it by 5 and added 7. I got 82. What was my number?
24. 24.Think of 4. Multiply it by 5, then add 2. What number do you end with?
25. 25.Magic trick! Think of 13. Double it, add 18, halve it, then take away 13. What number do you get?
26. 26.I thought of a number, multiplied it by 2 and added 9. I got 15. What was my number?
27. 27.Think of 6. Multiply it by 4, then add 3. What number do you end with?
28. 28.I thought of a number, multiplied it by 3 and added 1. I got 13. What was my number?
29. 29.Magic trick! Think of 18. Double it, add 8, halve it, then take away 18. What number do you get?
30. 30.I thought of a number, added 8 and then doubled it. I got 34. What was my number?
31. 31.Magic trick! Think of 2. Double it, add 6, halve it, then take away 2. What number do you get?
32. 32.Think of 13. Multiply it by 3, then add 5. What number do you end with?
33. 33.I thought of a number, added 1 and then doubled it. I got 8. What was my number?
34. 34.I thought of a number, added 6 and then doubled it. I got 48. What was my number?
35. 35.Magic trick! Think of 3. Double it, add 6, halve it, then take away 3. What number do you get?
36. 36.I thought of a number, added 9 and then doubled it. I got 56. What was my number?
37. 37.I thought of a number, added 6 and then doubled it. I got 26. What was my number?
38. 38.Magic trick! Think of 14. Double it, add 4, halve it, then take away 14. What number do you get?
39. 39.I thought of a number, added 4 and then doubled it. I got 20. What was my number?
40. 40.Think of 14. Multiply it by 5, then add 9. What number do you end with?

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