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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 870 · 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 37 and take away the sum of its digits. What do you get?
  2. 2.?404 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 61 and take away the sum of its digits. What do you get?
  4. 4.Take 30 and take away the sum of its digits. What do you get?
  5. 5.6?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?389 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.834? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.374? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 83 and take away the sum of its digits. What do you get?
  10. 10.66?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.8?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.32?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.352? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.182? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 14 and take away the sum of its digits. What do you get?
  18. 18.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.345? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?685 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.56?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.3?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 27 and take away the sum of its digits. What do you get?
  26. 26.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 71 and take away the sum of its digits. What do you get?
  28. 28.?946 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 51 and take away the sum of its digits. What do you get?
  30. 30.Take 97 and take away the sum of its digits. What do you get?
  31. 31.Take 25 and take away the sum of its digits. What do you get?
  32. 32.89?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.115? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 92 and take away the sum of its digits. What do you get?
  36. 36.?197 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.45?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 24 and take away the sum of its digits. What do you get?
  39. 39.1?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.508? 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. 1
  3. 54
  4. 27
  5. 8
  6. 7
  7. 3
  8. 4
  9. 72
  10. 6
  11. 4
  12. 1
  13. 8
  14. 7
  15. 3
  16. 7
  17. 9
  18. 6
  19. 6
  20. 8
  21. 3
  22. 7
  23. 7
  24. 7
  25. 18
  26. 6
  27. 63
  28. 8
  29. 45
  30. 81
  31. 18
  32. 1
  33. 4
  34. 2
  35. 81
  36. 1
  37. 2
  38. 18
  39. 6
  40. 5

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