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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 390 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.?080 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 54 and take away the sum of its digits. What do you get?
  4. 4.Take 26 and take away the sum of its digits. What do you get?
  5. 5.?968 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?039 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.657? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?899 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?893 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.431? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 82 and take away the sum of its digits. What do you get?
  15. 15.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.84?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.221? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?157 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 62 and take away the sum of its digits. What do you get?
  20. 20.67?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 36 and take away the sum of its digits. What do you get?
  22. 22.70?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 49 and take away the sum of its digits. What do you get?
  24. 24.Take 71 and take away the sum of its digits. What do you get?
  25. 25.7?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?385 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 15 and take away the sum of its digits. What do you get?
  28. 28.?167 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?627 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?002 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?948 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.408? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 66 and take away the sum of its digits. What do you get?
  34. 34.Take 27 and take away the sum of its digits. What do you get?
  35. 35.Take 32 and take away the sum of its digits. What do you get?
  36. 36.Take 13 and take away the sum of its digits. What do you get?
  37. 37.?896 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.31?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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