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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 728 · 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 29 and take away the sum of its digits. What do you get?
  2. 2.1?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?625 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.39? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?868 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.134? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 78 and take away the sum of its digits. What do you get?
  10. 10.Take 60 and take away the sum of its digits. What do you get?
  11. 11.23?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.63?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 77 and take away the sum of its digits. What do you get?
  14. 14.46?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 15 and take away the sum of its digits. What do you get?
  16. 16.Take 84 and take away the sum of its digits. What do you get?
  17. 17.6?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 76 and take away the sum of its digits. What do you get?
  19. 19.215? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 32 and take away the sum of its digits. What do you get?
  21. 21.546? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.775? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 61 and take away the sum of its digits. What do you get?
  24. 24.4?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.75?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?978 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.320? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.47?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 27 and take away the sum of its digits. What do you get?
  31. 31.Take 91 and take away the sum of its digits. What do you get?
  32. 32.Take 82 and take away the sum of its digits. What do you get?
  33. 33.8?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.75?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.534? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 75 and take away the sum of its digits. What do you get?
  38. 38.1?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.8?1 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. 8
  3. 5
  4. 6
  5. 9
  6. 5
  7. 1
  8. 5
  9. 63
  10. 54
  11. 6
  12. 4
  13. 63
  14. 8
  15. 9
  16. 72
  17. 1
  18. 63
  19. 1
  20. 27
  21. 3
  22. 8
  23. 54
  24. 7
  25. 4
  26. 3
  27. 4
  28. 8
  29. 7
  30. 18
  31. 81
  32. 72
  33. 4
  34. 2
  35. 6
  36. 2
  37. 63
  38. 6
  39. 7
  40. 9

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