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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 164 · 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. 1.83?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.1?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.179? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 69 and take away the sum of its digits. What do you get?
  5. 5.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 76 and take away the sum of its digits. What do you get?
  7. 7.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.39?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.71?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 85 and take away the sum of its digits. What do you get?
  11. 11.?661 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?984 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?443 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.47?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.26? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 36 and take away the sum of its digits. What do you get?
  18. 18.?629 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.405? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.67? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 46 and take away the sum of its digits. What do you get?
  22. 22.Take 75 and take away the sum of its digits. What do you get?
  23. 23.?677 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?505 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 49 and take away the sum of its digits. What do you get?
  26. 26.1?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 17 and take away the sum of its digits. What do you get?
  28. 28.412? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?337 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?327 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.8?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.349? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.67?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.82?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 41 and take away the sum of its digits. What do you get?
  36. 36.Take 84 and take away the sum of its digits. What do you get?
  37. 37.784? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.4?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.3?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.455? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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