← Think of a number lesson New set →

Think of a Number Puzzles Worksheet

Maths tricks trick 6: Think of a number · Set 77 · 40 questions
TalentJR

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.

NameDateTime takenScore ___ / 40
  1. 1.Think of 12. Multiply it by 5, then add 9. What number do you end with?
  2. 2.Magic trick! Think of 7. Double it, add 12, halve it, then take away 7. What number do you get?
  3. 3.I thought of a number, multiplied it by 2 and added 1. I got 25. What was my number?
  4. 4.I thought of a number, multiplied it by 2 and added 4. I got 30. What was my number?
  5. 5.I thought of a number, multiplied it by 4 and added 1. I got 33. What was my number?
  6. 6.I thought of a number, multiplied it by 4 and added 5. I got 65. What was my number?
  7. 7.Think of 9. Multiply it by 5, then add 8. What number do you end with?
  8. 8.I thought of a number, multiplied it by 5 and added 5. I got 70. What was my number?
  9. 9.I thought of a number, multiplied it by 3 and added 5. I got 44. What was my number?
  10. 10.I thought of a number, added 1 and then doubled it. I got 34. What was my number?
  11. 11.Magic trick! Think of 2. Double it, add 4, halve it, then take away 2. What number do you get?
  12. 12.I thought of a number, added 4 and then doubled it. I got 20. What was my number?
  13. 13.Magic trick! Think of 4. Double it, add 6, halve it, then take away 4. What number do you get?
  14. 14.I thought of a number, multiplied it by 4 and added 5. I got 57. What was my number?
  15. 15.I thought of a number, multiplied it by 2 and added 9. I got 31. What was my number?
  16. 16.Magic trick! Think of 17. Double it, add 6, halve it, then take away 17. What number do you get?
  17. 17.Magic trick! Think of 12. Double it, add 4, halve it, then take away 12. What number do you get?
  18. 18.I thought of a number, multiplied it by 5 and added 4. I got 54. What was my number?
  19. 19.Think of 14. Multiply it by 4, then add 7. What number do you end with?
  20. 20.I thought of a number, multiplied it by 5 and added 7. I got 67. What was my number?
  21. 21.I thought of a number, added 2 and then doubled it. I got 40. What was my number?
  22. 22.Magic trick! Think of 18. Double it, add 14, halve it, then take away 18. What number do you get?
  23. 23.I thought of a number, added 9 and then doubled it. I got 36. What was my number?
  24. 24.Magic trick! Think of 3. Double it, add 6, halve it, then take away 3. What number do you get?
  25. 25.I thought of a number, multiplied it by 3 and added 8. I got 26. What was my number?
  26. 26.Magic trick! Think of 3. Double it, add 16, halve it, then take away 3. What number do you get?
  27. 27.I thought of a number, added 4 and then doubled it. I got 46. What was my number?
  28. 28.Magic trick! Think of 18. Double it, add 18, halve it, then take away 18. What number do you get?
  29. 29.Magic trick! Think of 17. Double it, add 14, halve it, then take away 17. What number do you get?
  30. 30.I thought of a number, multiplied it by 4 and added 7. I got 55. What was my number?
  31. 31.Think of 14. Multiply it by 5, then add 9. What number do you end with?
  32. 32.Magic trick! Think of 12. Double it, add 10, halve it, then take away 12. What number do you get?
  33. 33.I thought of a number, multiplied it by 3 and added 2. I got 20. What was my number?
  34. 34.I thought of a number, multiplied it by 5 and added 2. I got 62. What was my number?
  35. 35.Magic trick! Think of 15. Double it, add 16, halve it, then take away 15. What number do you get?
  36. 36.Think of 4. Multiply it by 2, then add 5. What number do you end with?
  37. 37.Magic trick! Think of 5. Double it, add 4, halve it, then take away 5. What number do you get?
  38. 38.Think of 2. Multiply it by 2, then add 9. What number do you end with?
  39. 39.I thought of a number, added 4 and then doubled it. I got 14. What was my number?
  40. 40.I thought of a number, multiplied it by 3 and added 1. I got 25. What was my number?

Answer key

  1. 69
  2. 6
  3. 12
  4. 13
  5. 8
  6. 15
  7. 53
  8. 13
  9. 13
  10. 16
  11. 2
  12. 6
  13. 3
  14. 13
  15. 11
  16. 3
  17. 2
  18. 10
  19. 63
  20. 12
  21. 18
  22. 7
  23. 9
  24. 3
  25. 6
  26. 8
  27. 19
  28. 9
  29. 7
  30. 12
  31. 79
  32. 5
  33. 6
  34. 12
  35. 8
  36. 13
  37. 2
  38. 13
  39. 3
  40. 8

Free maths tricks lessons, practice and worksheets at talentjr.in/maths-tricks