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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 52 · 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 31 and take away the sum of its digits. What do you get?
  2. 2.Take 65 and take away the sum of its digits. What do you get?
  3. 3.70?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 28 and take away the sum of its digits. What do you get?
  5. 5.?507 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 64 and take away the sum of its digits. What do you get?
  7. 7.2?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?749 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 15 and take away the sum of its digits. What do you get?
  10. 10.Take 93 and take away the sum of its digits. What do you get?
  11. 11.3?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.87?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.182? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 90 and take away the sum of its digits. What do you get?
  16. 16.?923 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?195 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?453 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 99 and take away the sum of its digits. What do you get?
  22. 22.4?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 48 and take away the sum of its digits. What do you get?
  26. 26.118? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.210? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 84 and take away the sum of its digits. What do you get?
  29. 29.Take 94 and take away the sum of its digits. What do you get?
  30. 30.560? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.61? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 18 and take away the sum of its digits. What do you get?
  33. 33.?089 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.73?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.74?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?726 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.438? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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