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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 646 · 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. 1.1?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.780? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.199? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?413 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 92 and take away the sum of its digits. What do you get?
  10. 10.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?260 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 70 and take away the sum of its digits. What do you get?
  13. 13.1?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 49 and take away the sum of its digits. What do you get?
  15. 15.4?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?466 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?275 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 57 and take away the sum of its digits. What do you get?
  19. 19.Take 51 and take away the sum of its digits. What do you get?
  20. 20.Take 34 and take away the sum of its digits. What do you get?
  21. 21.Take 54 and take away the sum of its digits. What do you get?
  22. 22.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?903 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 24 and take away the sum of its digits. What do you get?
  25. 25.43?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.12?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  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 77 and take away the sum of its digits. What do you get?
  30. 30.Take 75 and take away the sum of its digits. What do you get?
  31. 31.8?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.86?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?795 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 30 and take away the sum of its digits. What do you get?
  35. 35.36?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?813 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?287 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.592? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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