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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 529 · 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. 1.663? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 59 and take away the sum of its digits. What do you get?
  4. 4.8?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.79?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.791? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 94 and take away the sum of its digits. What do you get?
  8. 8.7?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.57?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 90 and take away the sum of its digits. What do you get?
  11. 11.Take 27 and take away the sum of its digits. What do you get?
  12. 12.Take 98 and take away the sum of its digits. What do you get?
  13. 13.657? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 88 and take away the sum of its digits. What do you get?
  16. 16.2?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?480 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?766 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.4?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?271 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 76 and take away the sum of its digits. What do you get?
  25. 25.Take 82 and take away the sum of its digits. What do you get?
  26. 26.?555 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 12 and take away the sum of its digits. What do you get?
  28. 28.53? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 11 and take away the sum of its digits. What do you get?
  30. 30.Take 28 and take away the sum of its digits. What do you get?
  31. 31.?508 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.63?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?841 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.125? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.664? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.59?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 45 and take away the sum of its digits. What do you get?
  39. 39.Take 22 and take away the sum of its digits. What do you get?
  40. 40.17?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 6
  3. 45
  4. 9
  5. 2
  6. 1
  7. 81
  8. 8
  9. 8
  10. 81
  11. 18
  12. 81
  13. 9
  14. 8
  15. 72
  16. 9
  17. 6
  18. 8
  19. 7
  20. 2
  21. 5
  22. 4
  23. 8
  24. 63
  25. 72
  26. 3
  27. 9
  28. 1
  29. 9
  30. 18
  31. 5
  32. 9
  33. 4
  34. 5
  35. 1
  36. 2
  37. 4
  38. 36
  39. 18
  40. 1

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