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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 777 · 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.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.326? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.3?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 68 and take away the sum of its digits. What do you get?
  5. 5.283? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.74?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 24 and take away the sum of its digits. What do you get?
  9. 9.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.23?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 80 and take away the sum of its digits. What do you get?
  13. 13.Take 61 and take away the sum of its digits. What do you get?
  14. 14.Take 38 and take away the sum of its digits. What do you get?
  15. 15.8?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.769? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.12?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 48 and take away the sum of its digits. What do you get?
  19. 19.?713 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 89 and take away the sum of its digits. What do you get?
  21. 21.16?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 16 and take away the sum of its digits. What do you get?
  23. 23.Take 88 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. 25.23?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.404? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.571? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?112 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.15?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 73 and take away the sum of its digits. What do you get?
  34. 34.Take 41 and take away the sum of its digits. What do you get?
  35. 35.1?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 32 and take away the sum of its digits. What do you get?
  37. 37.899? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.785? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?226 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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