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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 845 · 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 94 and take away the sum of its digits. What do you get?
  2. 2.Take 67 and take away the sum of its digits. What do you get?
  3. 3.Take 13 and take away the sum of its digits. What do you get?
  4. 4.244? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.4?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.404? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.12?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.808? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?214 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.49?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 83 and take away the sum of its digits. What do you get?
  15. 15.8?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?841 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.40?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.21?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 95 and take away the sum of its digits. What do you get?
  21. 21.Take 51 and take away the sum of its digits. What do you get?
  22. 22.58?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.17?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?807 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?268 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.3?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.160? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 11 and take away the sum of its digits. What do you get?
  29. 29.?619 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.732? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?221 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 23 and take away the sum of its digits. What do you get?
  33. 33.?617 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 27 and take away the sum of its digits. What do you get?
  35. 35.81?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.4?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 20 and take away the sum of its digits. What do you get?
  39. 39.607? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 30 and take away the sum of its digits. What do you get?

Answer key

  1. 81
  2. 54
  3. 9
  4. 8
  5. 9
  6. 2
  7. 1
  8. 9
  9. 9
  10. 2
  11. 5
  12. 2
  13. 4
  14. 72
  15. 6
  16. 5
  17. 4
  18. 9
  19. 2
  20. 81
  21. 45
  22. 2
  23. 8
  24. 3
  25. 2
  26. 3
  27. 2
  28. 9
  29. 2
  30. 6
  31. 4
  32. 18
  33. 4
  34. 18
  35. 3
  36. 1
  37. 1
  38. 18
  39. 5
  40. 27

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