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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 473 · 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. 1.577? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 75 and take away the sum of its digits. What do you get?
  3. 3.?048 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.33?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 40 and take away the sum of its digits. What do you get?
  6. 6.4?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?869 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?991 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.527? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 90 and take away the sum of its digits. What do you get?
  12. 12.?814 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 53 and take away the sum of its digits. What do you get?
  14. 14.Take 97 and take away the sum of its digits. What do you get?
  15. 15.?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 24 and take away the sum of its digits. What do you get?
  17. 17.Take 39 and take away the sum of its digits. What do you get?
  18. 18.Take 68 and take away the sum of its digits. What do you get?
  19. 19.Take 58 and take away the sum of its digits. What do you get?
  20. 20.441? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 14 and take away the sum of its digits. What do you get?
  23. 23.746? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 96 and take away the sum of its digits. What do you get?
  25. 25.Take 77 and take away the sum of its digits. What do you get?
  26. 26.19? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 36 and take away the sum of its digits. What do you get?
  28. 28.Take 55 and take away the sum of its digits. What do you get?
  29. 29.89?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.60?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?866 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 67 and take away the sum of its digits. What do you get?
  33. 33.Take 86 and take away the sum of its digits. What do you get?
  34. 34.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 78 and take away the sum of its digits. What do you get?
  36. 36.?601 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.17?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.78?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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