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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 80 · 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.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.87?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.323? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?830 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?788 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 82 and take away the sum of its digits. What do you get?
  7. 7.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 29 and take away the sum of its digits. What do you get?
  9. 9.698? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.70?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?827 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 12 and take away the sum of its digits. What do you get?
  14. 14.Take 39 and take away the sum of its digits. What do you get?
  15. 15.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 16 and take away the sum of its digits. What do you get?
  17. 17.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.18?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 33 and take away the sum of its digits. What do you get?
  23. 23.219? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 89 and take away the sum of its digits. What do you get?
  25. 25.2?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 78 and take away the sum of its digits. What do you get?
  28. 28.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?793 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.5?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?764 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.178? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?887 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?688 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?742 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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