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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 708 · 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. 1.28?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.805? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 81 and take away the sum of its digits. What do you get?
  4. 4.7?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 73 and take away the sum of its digits. What do you get?
  6. 6.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 65 and take away the sum of its digits. What do you get?
  8. 8.64?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.43?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 72 and take away the sum of its digits. What do you get?
  11. 11.?503 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.606? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 24 and take away the sum of its digits. What do you get?
  16. 16.79?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 37 and take away the sum of its digits. What do you get?
  18. 18.7?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.250? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.601? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 13 and take away the sum of its digits. What do you get?
  22. 22.3?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.52?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 66 and take away the sum of its digits. What do you get?
  26. 26.Take 21 and take away the sum of its digits. What do you get?
  27. 27.68?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.4?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 51 and take away the sum of its digits. What do you get?
  31. 31.2?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 69 and take away the sum of its digits. What do you get?
  33. 33.?978 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 84 and take away the sum of its digits. What do you get?
  36. 36.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 18 and take away the sum of its digits. What do you get?
  38. 38.20?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 96 and take away the sum of its digits. What do you get?
  40. 40.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 5
  2. 5
  3. 72
  4. 1
  5. 63
  6. 6
  7. 54
  8. 3
  9. 2
  10. 63
  11. 1
  12. 9
  13. 54
  14. 6
  15. 18
  16. 3
  17. 27
  18. 4
  19. 2
  20. 2
  21. 9
  22. 7
  23. 7
  24. 1
  25. 54
  26. 18
  27. 4
  28. 9
  29. 6
  30. 45
  31. 3
  32. 54
  33. 3
  34. 5
  35. 72
  36. 8
  37. 9
  38. 5
  39. 81
  40. 3

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