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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 975 · 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 43 and take away the sum of its digits. What do you get?
  2. 2.Take 60 and take away the sum of its digits. What do you get?
  3. 3.Take 81 and take away the sum of its digits. What do you get?
  4. 4.6?66 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. 6.24?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?832 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?632 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.38?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?876 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.3?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.55?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.172? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 26 and take away the sum of its digits. What do you get?
  18. 18.?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?974 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 27 and take away the sum of its digits. What do you get?
  21. 21.54?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 57 and take away the sum of its digits. What do you get?
  23. 23.442? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.5?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 80 and take away the sum of its digits. What do you get?
  27. 27.Take 54 and take away the sum of its digits. What do you get?
  28. 28.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.33?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 46 and take away the sum of its digits. What do you get?
  31. 31.Take 93 and take away the sum of its digits. What do you get?
  32. 32.6?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 51 and take away the sum of its digits. What do you get?
  34. 34.Take 89 and take away the sum of its digits. What do you get?
  35. 35.2?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.656? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.612? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 66 and take away the sum of its digits. What do you get?
  39. 39.Take 32 and take away the sum of its digits. What do you get?
  40. 40.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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