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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 110 · 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. 1.3?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.6?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.41?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.6?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.78?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 57 and take away the sum of its digits. What do you get?
  9. 9.38? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?710 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?968 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 94 and take away the sum of its digits. What do you get?
  15. 15.54? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.301? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.374? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.37?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 32 and take away the sum of its digits. What do you get?
  21. 21.?547 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 23 and take away the sum of its digits. What do you get?
  23. 23.4?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.2?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.171? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.17?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.16?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 19 and take away the sum of its digits. What do you get?
  30. 30.?893 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?701 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.441? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 18 and take away the sum of its digits. What do you get?
  35. 35.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.274? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?916 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.598? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.21?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.512? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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