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Think of a Number Puzzles Worksheet

Maths tricks trick 6: Think of a number · Set 95 · 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 8. Multiply it by 4, then add 7. What number do you end with?
  2. 2.Magic trick! Think of 13. Double it, add 18, halve it, then take away 13. What number do you get?
  3. 3.Think of 9. Multiply it by 3, then add 7. What number do you end with?
  4. 4.I thought of a number, multiplied it by 4 and added 1. I got 57. What was my number?
  5. 5.Magic trick! Think of 12. Double it, add 4, halve it, then take away 12. What number do you get?
  6. 6.Magic trick! Think of 7. Double it, add 4, halve it, then take away 7. What number do you get?
  7. 7.I thought of a number, multiplied it by 2 and added 2. I got 20. What was my number?
  8. 8.Magic trick! Think of 11. Double it, add 14, halve it, then take away 11. What number do you get?
  9. 9.I thought of a number, multiplied it by 5 and added 8. I got 33. What was my number?
  10. 10.Magic trick! Think of 9. Double it, add 4, halve it, then take away 9. What number do you get?
  11. 11.Magic trick! Think of 8. Double it, add 4, halve it, then take away 8. What number do you get?
  12. 12.Magic trick! Think of 13. Double it, add 10, halve it, then take away 13. What number do you get?
  13. 13.Think of 14. Multiply it by 3, then add 4. What number do you end with?
  14. 14.Magic trick! Think of 9. Double it, add 10, halve it, then take away 9. What number do you get?
  15. 15.Think of 14. Multiply it by 4, then add 1. What number do you end with?
  16. 16.I thought of a number, added 8 and then doubled it. I got 34. What was my number?
  17. 17.Magic trick! Think of 10. Double it, add 12, halve it, then take away 10. What number do you get?
  18. 18.I thought of a number, added 2 and then doubled it. I got 10. What was my number?
  19. 19.I thought of a number, multiplied it by 2 and added 3. I got 23. What was my number?
  20. 20.Think of 6. Multiply it by 5, then add 3. What number do you end with?
  21. 21.I thought of a number, added 9 and then doubled it. I got 36. What was my number?
  22. 22.Magic trick! Think of 11. Double it, add 4, halve it, then take away 11. What number do you get?
  23. 23.Magic trick! Think of 17. Double it, add 16, halve it, then take away 17. What number do you get?
  24. 24.I thought of a number, multiplied it by 2 and added 3. I got 9. What was my number?
  25. 25.Think of 7. Multiply it by 2, then add 2. What number do you end with?
  26. 26.Magic trick! Think of 16. Double it, add 18, halve it, then take away 16. What number do you get?
  27. 27.Magic trick! Think of 12. Double it, add 10, halve it, then take away 12. What number do you get?
  28. 28.I thought of a number, added 7 and then doubled it. I got 36. What was my number?
  29. 29.Magic trick! Think of 8. Double it, add 10, halve it, then take away 8. What number do you get?
  30. 30.Think of 4. Multiply it by 3, then add 2. What number do you end with?
  31. 31.Magic trick! Think of 6. Double it, add 14, halve it, then take away 6. What number do you get?
  32. 32.Think of 2. Multiply it by 5, then add 4. What number do you end with?
  33. 33.I thought of a number, multiplied it by 2 and added 2. I got 22. What was my number?
  34. 34.I thought of a number, multiplied it by 4 and added 8. I got 32. What was my number?
  35. 35.I thought of a number, added 2 and then doubled it. I got 24. What was my number?
  36. 36.I thought of a number, added 3 and then doubled it. I got 32. What was my number?
  37. 37.Magic trick! Think of 10. Double it, add 10, halve it, then take away 10. What number do you get?
  38. 38.Magic trick! Think of 6. Double it, add 6, halve it, then take away 6. What number do you get?
  39. 39.I thought of a number, multiplied it by 3 and added 1. I got 25. What was my number?
  40. 40.I thought of a number, added 5 and then doubled it. I got 44. What was my number?

Answer key

  1. 39
  2. 9
  3. 34
  4. 14
  5. 2
  6. 2
  7. 9
  8. 7
  9. 5
  10. 2
  11. 2
  12. 5
  13. 46
  14. 5
  15. 57
  16. 9
  17. 6
  18. 3
  19. 10
  20. 33
  21. 9
  22. 2
  23. 8
  24. 3
  25. 16
  26. 9
  27. 5
  28. 11
  29. 5
  30. 14
  31. 7
  32. 14
  33. 10
  34. 6
  35. 10
  36. 13
  37. 5
  38. 3
  39. 8
  40. 17

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