Think of a Number Puzzles Worksheet

Maths tricks trick 6: Think of a number · Set 209 · 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 30. What was my number?
2. 2.Think of 11. Multiply it by 4, then add 9. What number do you end with?
3. 3.I thought of a number, multiplied it by 5 and added 2. I got 47. What was my number?
4. 4.Think of 7. Multiply it by 5, then add 2. What number do you end with?
5. 5.Think of 5. Multiply it by 3, then add 9. What number do you end with?
6. 6.Magic trick! Think of 3. Double it, add 10, halve it, then take away 3. What number do you get?
7. 7.Think of 8. Multiply it by 2, then add 9. What number do you end with?
8. 8.Think of 2. Multiply it by 4, then add 7. What number do you end with?
9. 9.I thought of a number, added 3 and then doubled it. I got 20. What was my number?
10. 10.Think of 8. Multiply it by 5, then add 1. What number do you end with?
11. 11.Think of 5. Multiply it by 3, then add 4. What number do you end with?
12. 12.Think of 8. Multiply it by 4, then add 7. What number do you end with?
13. 13.Think of 11. Multiply it by 5, then add 1. What number do you end with?
14. 14.Think of 8. Multiply it by 2, then add 7. What number do you end with?
15. 15.I thought of a number, multiplied it by 2 and added 1. I got 5. What was my number?
16. 16.I thought of a number, multiplied it by 2 and added 3. I got 29. What was my number?
17. 17.I thought of a number, added 1 and then doubled it. I got 26. What was my number?
18. 18.Think of 7. Multiply it by 2, then add 6. What number do you end with?
19. 19.I thought of a number, added 3 and then doubled it. I got 42. What was my number?
20. 20.Magic trick! Think of 12. Double it, add 4, halve it, then take away 12. What number do you get?
21. 21.I thought of a number, multiplied it by 2 and added 9. I got 35. What was my number?
22. 22.Magic trick! Think of 8. Double it, add 18, halve it, then take away 8. What number do you get?
23. 23.Think of 3. Multiply it by 4, then add 7. What number do you end with?
24. 24.I thought of a number, multiplied it by 5 and added 3. I got 13. What was my number?
25. 25.Magic trick! Think of 4. Double it, add 4, halve it, then take away 4. What number do you get?
26. 26.I thought of a number, multiplied it by 3 and added 6. I got 12. What was my number?
27. 27.Magic trick! Think of 17. Double it, add 12, halve it, then take away 17. What number do you get?
28. 28.Magic trick! Think of 8. Double it, add 16, halve it, then take away 8. What number do you get?
29. 29.I thought of a number, added 4 and then doubled it. I got 28. What was my number?
30. 30.Magic trick! Think of 19. Double it, add 12, halve it, then take away 19. What number do you get?
31. 31.I thought of a number, added 2 and then doubled it. I got 24. What was my number?
32. 32.Think of 4. Multiply it by 2, then add 4. What number do you end with?
33. 33.I thought of a number, multiplied it by 4 and added 1. I got 57. What was my number?
34. 34.I thought of a number, multiplied it by 4 and added 4. I got 28. What was my number?
35. 35.Magic trick! Think of 5. Double it, add 4, halve it, then take away 5. What number do you get?
36. 36.Think of 11. Multiply it by 3, then add 2. What number do you end with?
37. 37.I thought of a number, multiplied it by 4 and added 5. I got 45. What was my number?
38. 38.I thought of a number, multiplied it by 3 and added 7. I got 25. What was my number?
39. 39.I thought of a number, added 2 and then doubled it. I got 36. What was my number?
40. 40.I thought of a number, multiplied it by 4 and added 2. I got 62. What was my number?

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