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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 14 · 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 66 and take away the sum of its digits. What do you get?
  2. 2.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.4?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?095 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?892 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?489 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 44 and take away the sum of its digits. What do you get?
  10. 10.894? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.19?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?129 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?559 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?777 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.607? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.325? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 56 and take away the sum of its digits. What do you get?
  20. 20.20?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 45 and take away the sum of its digits. What do you get?
  22. 22.?994 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 82 and take away the sum of its digits. What do you get?
  26. 26.28?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.544? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 69 and take away the sum of its digits. What do you get?
  29. 29.4?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.76?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?677 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.8?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.6?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?163 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.444? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 24 and take away the sum of its digits. What do you get?
  38. 38.576? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.87?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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