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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 256 · 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. 1.1?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.82?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 38 and take away the sum of its digits. What do you get?
  5. 5.Take 18 and take away the sum of its digits. What do you get?
  6. 6.7?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 63 and take away the sum of its digits. What do you get?
  8. 8.Take 71 and take away the sum of its digits. What do you get?
  9. 9.Take 54 and take away the sum of its digits. What do you get?
  10. 10.Take 11 and take away the sum of its digits. What do you get?
  11. 11.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.54?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?650 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?899 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 39 and take away the sum of its digits. What do you get?
  16. 16.49?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.62? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.2?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.69?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?919 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 62 and take away the sum of its digits. What do you get?
  22. 22.?085 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?586 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.88?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.688? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?042 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 91 and take away the sum of its digits. What do you get?
  32. 32.7?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.32?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.785? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.10?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 79 and take away the sum of its digits. What do you get?
  37. 37.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 92 and take away the sum of its digits. What do you get?
  39. 39.?424 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.260? 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. 3
  3. 5
  4. 27
  5. 9
  6. 5
  7. 54
  8. 63
  9. 45
  10. 9
  11. 7
  12. 1
  13. 7
  14. 1
  15. 27
  16. 4
  17. 1
  18. 6
  19. 8
  20. 8
  21. 54
  22. 5
  23. 9
  24. 8
  25. 7
  26. 1
  27. 5
  28. 3
  29. 1
  30. 6
  31. 81
  32. 7
  33. 9
  34. 7
  35. 7
  36. 63
  37. 5
  38. 81
  39. 8
  40. 1

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