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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 616 · 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. 1.3?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.86?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.489? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?538 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.24?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.787? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.32?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?689 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 52 and take away the sum of its digits. What do you get?
  12. 12.1?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 35 and take away the sum of its digits. What do you get?
  14. 14.77?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 21 and take away the sum of its digits. What do you get?
  16. 16.Take 90 and take away the sum of its digits. What do you get?
  17. 17.79?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.8?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?794 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 62 and take away the sum of its digits. What do you get?
  24. 24.Take 25 and take away the sum of its digits. What do you get?
  25. 25.20?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.593? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 31 and take away the sum of its digits. What do you get?
  28. 28.Take 99 and take away the sum of its digits. What do you get?
  29. 29.603? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.43?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.72?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 81 and take away the sum of its digits. What do you get?
  33. 33.1?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?042 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 85 and take away the sum of its digits. What do you get?
  36. 36.Take 98 and take away the sum of its digits. What do you get?
  37. 37.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.7?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.17?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?575 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 4
  2. 7
  3. 6
  4. 2
  5. 3
  6. 2
  7. 5
  8. 6
  9. 6
  10. 4
  11. 45
  12. 8
  13. 27
  14. 1
  15. 18
  16. 81
  17. 1
  18. 4
  19. 3
  20. 6
  21. 3
  22. 7
  23. 54
  24. 18
  25. 5
  26. 1
  27. 27
  28. 81
  29. 9
  30. 5
  31. 1
  32. 72
  33. 8
  34. 3
  35. 72
  36. 81
  37. 4
  38. 8
  39. 7
  40. 1

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