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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 90 · 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.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 29 and take away the sum of its digits. What do you get?
  3. 3.Take 92 and take away the sum of its digits. What do you get?
  4. 4.?939 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.4?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.776? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.58?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 82 and take away the sum of its digits. What do you get?
  9. 9.Take 76 and take away the sum of its digits. What do you get?
  10. 10.Take 31 and take away the sum of its digits. What do you get?
  11. 11.?048 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.46?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 11 and take away the sum of its digits. What do you get?
  14. 14.Take 69 and take away the sum of its digits. What do you get?
  15. 15.Take 18 and take away the sum of its digits. What do you get?
  16. 16.?071 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?146 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.55?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.68?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.80?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.8?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 88 and take away the sum of its digits. What do you get?
  26. 26.Take 15 and take away the sum of its digits. What do you get?
  27. 27.?462 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.847? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.202? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 96 and take away the sum of its digits. What do you get?
  31. 31.Take 28 and take away the sum of its digits. What do you get?
  32. 32.370? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.87?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?110 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.487? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.817? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?946 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 47 and take away the sum of its digits. What do you get?
  40. 40.Take 62 and take away the sum of its digits. What do you get?

Answer key

  1. 5
  2. 18
  3. 81
  4. 6
  5. 6
  6. 7
  7. 6
  8. 72
  9. 63
  10. 27
  11. 6
  12. 7
  13. 9
  14. 54
  15. 9
  16. 1
  17. 7
  18. 1
  19. 7
  20. 5
  21. 1
  22. 4
  23. 9
  24. 4
  25. 72
  26. 9
  27. 6
  28. 8
  29. 5
  30. 81
  31. 18
  32. 8
  33. 4
  34. 5
  35. 7
  36. 8
  37. 2
  38. 8
  39. 36
  40. 54

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