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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 923 · 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. 1.47?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.4?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.4?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 24 and take away the sum of its digits. What do you get?
  5. 5.Take 94 and take away the sum of its digits. What do you get?
  6. 6.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.673? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.10?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.724? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.72?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 15 and take away the sum of its digits. What do you get?
  14. 14.Take 57 and take away the sum of its digits. What do you get?
  15. 15.57? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.13? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?979 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.56?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 30 and take away the sum of its digits. What do you get?
  20. 20.Take 70 and take away the sum of its digits. What do you get?
  21. 21.Take 13 and take away the sum of its digits. What do you get?
  22. 22.691? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 52 and take away the sum of its digits. What do you get?
  24. 24.26?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.59?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 76 and take away the sum of its digits. What do you get?
  27. 27.?147 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 81 and take away the sum of its digits. What do you get?
  29. 29.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 47 and take away the sum of its digits. What do you get?
  32. 32.251? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.56?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 12 and take away the sum of its digits. What do you get?
  35. 35.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?125 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?760 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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