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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 239 · 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. 1.846? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?958 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 47 and take away the sum of its digits. What do you get?
  4. 4.7?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.8?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 20 and take away the sum of its digits. What do you get?
  9. 9.4?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?978 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 78 and take away the sum of its digits. What do you get?
  13. 13.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 60 and take away the sum of its digits. What do you get?
  15. 15.14? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.406? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?338 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 24 and take away the sum of its digits. What do you get?
  20. 20.Take 45 and take away the sum of its digits. What do you get?
  21. 21.Take 64 and take away the sum of its digits. What do you get?
  22. 22.Take 74 and take away the sum of its digits. What do you get?
  23. 23.?962 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.463? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 27 and take away the sum of its digits. What do you get?
  26. 26.Take 25 and take away the sum of its digits. What do you get?
  27. 27.Take 30 and take away the sum of its digits. What do you get?
  28. 28.Take 70 and take away the sum of its digits. What do you get?
  29. 29.Take 53 and take away the sum of its digits. What do you get?
  30. 30.599? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.25?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 82 and take away the sum of its digits. What do you get?
  36. 36.?939 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.411? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.74?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 91 and take away the sum of its digits. What do you get?
  40. 40.546? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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