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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 519 · 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.Take 66 and take away the sum of its digits. What do you get?
  2. 2.Take 40 and take away the sum of its digits. What do you get?
  3. 3.60?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?404 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.33?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 31 and take away the sum of its digits. What do you get?
  9. 9.?399 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 28 and take away the sum of its digits. What do you get?
  12. 12.?813 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?482 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 61 and take away the sum of its digits. What do you get?
  17. 17.?035 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?777 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.235? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 97 and take away the sum of its digits. What do you get?
  21. 21.53?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 76 and take away the sum of its digits. What do you get?
  23. 23.Take 73 and take away the sum of its digits. What do you get?
  24. 24.652? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?386 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 86 and take away the sum of its digits. What do you get?
  27. 27.643? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 51 and take away the sum of its digits. What do you get?
  30. 30.8?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?295 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?966 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.6?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.88?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?426 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.460? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.80?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.40?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 71 and take away the sum of its digits. What do you get?

Answer key

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

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