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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 266 · 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. 1.56?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.319? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.56?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.23?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.828? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 58 and take away the sum of its digits. What do you get?
  9. 9.106? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 87 and take away the sum of its digits. What do you get?
  11. 11.Take 57 and take away the sum of its digits. What do you get?
  12. 12.Take 31 and take away the sum of its digits. What do you get?
  13. 13.170? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.13? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.57?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 54 and take away the sum of its digits. What do you get?
  20. 20.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?313 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.44?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.242? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.34?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.161? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.42?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?671 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?285 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?958 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 50 and take away the sum of its digits. What do you get?
  32. 32.Take 74 and take away the sum of its digits. What do you get?
  33. 33.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 13 and take away the sum of its digits. What do you get?
  35. 35.?329 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 30 and take away the sum of its digits. What do you get?
  37. 37.?776 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 26 and take away the sum of its digits. What do you get?

Answer key

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

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