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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 92 · 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 61 and take away the sum of its digits. What do you get?
  3. 3.?740 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 82 and take away the sum of its digits. What do you get?
  5. 5.?129 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 58 and take away the sum of its digits. What do you get?
  7. 7.822? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.1?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.102? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.5?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 77 and take away the sum of its digits. What do you get?
  13. 13.594? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.629? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.23?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.86?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?703 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 18 and take away the sum of its digits. What do you get?
  20. 20.Take 25 and take away the sum of its digits. What do you get?
  21. 21.63?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?638 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?940 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 47 and take away the sum of its digits. What do you get?
  26. 26.?281 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?912 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.78?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.186? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.2?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.5?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?246 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?295 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.6?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 84 and take away the sum of its digits. What do you get?

Answer key

  1. 27
  2. 54
  3. 7
  4. 72
  5. 6
  6. 45
  7. 6
  8. 1
  9. 6
  10. 6
  11. 9
  12. 63
  13. 9
  14. 1
  15. 9
  16. 4
  17. 6
  18. 8
  19. 9
  20. 18
  21. 9
  22. 6
  23. 1
  24. 5
  25. 36
  26. 7
  27. 6
  28. 2
  29. 9
  30. 3
  31. 3
  32. 6
  33. 4
  34. 8
  35. 6
  36. 2
  37. 4
  38. 2
  39. 8
  40. 72

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