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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 388 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.Take 71 and take away the sum of its digits. What do you get?
  2. 2.25?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?728 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 21 and take away the sum of its digits. What do you get?
  6. 6.43? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 13 and take away the sum of its digits. What do you get?
  8. 8.Take 33 and take away the sum of its digits. What do you get?
  9. 9.Take 31 and take away the sum of its digits. What do you get?
  10. 10.Take 55 and take away the sum of its digits. What do you get?
  11. 11.87?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?529 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.11?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?987 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 34 and take away the sum of its digits. What do you get?
  18. 18.?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 32 and take away the sum of its digits. What do you get?
  20. 20.28?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.107? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.57?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 14 and take away the sum of its digits. What do you get?
  25. 25.?219 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 79 and take away the sum of its digits. What do you get?
  27. 27.240? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.552? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 57 and take away the sum of its digits. What do you get?
  31. 31.2?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.342? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 97 and take away the sum of its digits. What do you get?
  34. 34.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 54 and take away the sum of its digits. What do you get?
  36. 36.Take 30 and take away the sum of its digits. What do you get?
  37. 37.?140 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.704? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.25?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 63
  2. 5
  3. 1
  4. 3
  5. 18
  6. 2
  7. 9
  8. 27
  9. 27
  10. 45
  11. 1
  12. 2
  13. 9
  14. 3
  15. 4
  16. 3
  17. 27
  18. 1
  19. 27
  20. 4
  21. 1
  22. 1
  23. 9
  24. 9
  25. 6
  26. 63
  27. 3
  28. 4
  29. 6
  30. 45
  31. 3
  32. 9
  33. 81
  34. 1
  35. 45
  36. 27
  37. 4
  38. 7
  39. 4
  40. 4

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