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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 731 · 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. 1.45?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 63 and take away the sum of its digits. What do you get?
  4. 4.?944 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 17 and take away the sum of its digits. What do you get?
  6. 6.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.17?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?285 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?816 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.340? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?674 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.39?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.598? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.698? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?897 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 42 and take away the sum of its digits. What do you get?
  21. 21.?398 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?091 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?682 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 23 and take away the sum of its digits. What do you get?
  25. 25.?218 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.4?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.290? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 39 and take away the sum of its digits. What do you get?
  30. 30.Take 51 and take away the sum of its digits. What do you get?
  31. 31.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 66 and take away the sum of its digits. What do you get?
  33. 33.Take 11 and take away the sum of its digits. What do you get?
  34. 34.6?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.591? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.235? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 15 and take away the sum of its digits. What do you get?
  39. 39.Take 50 and take away the sum of its digits. What do you get?
  40. 40.Take 54 and take away the sum of its digits. What do you get?

Answer key

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

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