← Think of a number lesson New set →

Think of a Number Puzzles Worksheet

Maths tricks trick 6: Think of a number · Set 105 · 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.I thought of a number, added 6 and then doubled it. I got 20. What was my number?
  2. 2.Magic trick! Think of 14. Double it, add 8, halve it, then take away 14. What number do you get?
  3. 3.Magic trick! Think of 7. Double it, add 18, halve it, then take away 7. What number do you get?
  4. 4.I thought of a number, multiplied it by 5 and added 9. I got 49. What was my number?
  5. 5.I thought of a number, added 8 and then doubled it. I got 52. What was my number?
  6. 6.Think of 13. Multiply it by 3, then add 8. What number do you end with?
  7. 7.Magic trick! Think of 6. Double it, add 4, halve it, then take away 6. What number do you get?
  8. 8.Think of 12. Multiply it by 5, then add 5. What number do you end with?
  9. 9.Think of 8. Multiply it by 3, then add 2. What number do you end with?
  10. 10.I thought of a number, added 2 and then doubled it. I got 18. What was my number?
  11. 11.I thought of a number, added 1 and then doubled it. I got 30. What was my number?
  12. 12.Think of 10. Multiply it by 4, then add 3. What number do you end with?
  13. 13.Think of 11. Multiply it by 5, then add 2. What number do you end with?
  14. 14.Think of 14. Multiply it by 2, then add 3. What number do you end with?
  15. 15.Think of 6. Multiply it by 2, then add 4. What number do you end with?
  16. 16.Think of 7. Multiply it by 2, then add 8. What number do you end with?
  17. 17.Think of 14. Multiply it by 2, then add 5. What number do you end with?
  18. 18.Magic trick! Think of 14. Double it, add 6, halve it, then take away 14. What number do you get?
  19. 19.I thought of a number, added 2 and then doubled it. I got 40. What was my number?
  20. 20.I thought of a number, multiplied it by 4 and added 3. I got 43. What was my number?
  21. 21.I thought of a number, multiplied it by 2 and added 3. I got 13. What was my number?
  22. 22.I thought of a number, added 5 and then doubled it. I got 28. What was my number?
  23. 23.Think of 11. Multiply it by 5, then add 5. What number do you end with?
  24. 24.Magic trick! Think of 8. Double it, add 4, halve it, then take away 8. What number do you get?
  25. 25.Magic trick! Think of 5. Double it, add 4, halve it, then take away 5. What number do you get?
  26. 26.I thought of a number, added 9 and then doubled it. I got 44. What was my number?
  27. 27.I thought of a number, multiplied it by 4 and added 9. I got 57. What was my number?
  28. 28.Magic trick! Think of 16. Double it, add 14, halve it, then take away 16. What number do you get?
  29. 29.Magic trick! Think of 5. Double it, add 12, halve it, then take away 5. What number do you get?
  30. 30.I thought of a number, added 3 and then doubled it. I got 12. What was my number?
  31. 31.I thought of a number, multiplied it by 2 and added 5. I got 29. What was my number?
  32. 32.I thought of a number, added 7 and then doubled it. I got 52. What was my number?
  33. 33.I thought of a number, multiplied it by 3 and added 8. I got 14. What was my number?
  34. 34.Think of 13. Multiply it by 5, then add 4. What number do you end with?
  35. 35.I thought of a number, multiplied it by 2 and added 5. I got 35. What was my number?
  36. 36.I thought of a number, added 4 and then doubled it. I got 40. What was my number?
  37. 37.Think of 10. Multiply it by 5, then add 1. What number do you end with?
  38. 38.I thought of a number, added 5 and then doubled it. I got 46. What was my number?
  39. 39.I thought of a number, multiplied it by 5 and added 6. I got 41. What was my number?
  40. 40.Magic trick! Think of 17. Double it, add 12, halve it, then take away 17. What number do you get?

Answer key

  1. 4
  2. 4
  3. 9
  4. 8
  5. 18
  6. 47
  7. 2
  8. 65
  9. 26
  10. 7
  11. 14
  12. 43
  13. 57
  14. 31
  15. 16
  16. 22
  17. 33
  18. 3
  19. 18
  20. 10
  21. 5
  22. 9
  23. 60
  24. 2
  25. 2
  26. 13
  27. 12
  28. 7
  29. 6
  30. 3
  31. 12
  32. 19
  33. 2
  34. 69
  35. 15
  36. 16
  37. 51
  38. 18
  39. 7
  40. 6

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