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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 556 · 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 25 and take away the sum of its digits. What do you get?
  2. 2.8?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?988 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.182? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.1?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 36 and take away the sum of its digits. What do you get?
  8. 8.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.480? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 16 and take away the sum of its digits. What do you get?
  11. 11.?361 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 14 and take away the sum of its digits. What do you get?
  13. 13.79?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.85?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.46?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.2?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.124? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?985 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 75 and take away the sum of its digits. What do you get?
  21. 21.Take 31 and take away the sum of its digits. What do you get?
  22. 22.Take 54 and take away the sum of its digits. What do you get?
  23. 23.?605 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 99 and take away the sum of its digits. What do you get?
  25. 25.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.248? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 63 and take away the sum of its digits. What do you get?
  29. 29.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?905 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.498? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?499 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 37 and take away the sum of its digits. What do you get?
  36. 36.2?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?551 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.47?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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