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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 996 · 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 77 and take away the sum of its digits. What do you get?
  2. 2.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?318 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.49?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.329? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.20?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.3?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?763 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.825? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.4?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 21 and take away the sum of its digits. What do you get?
  13. 13.96? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?565 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 81 and take away the sum of its digits. What do you get?
  17. 17.Take 88 and take away the sum of its digits. What do you get?
  18. 18.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.61?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?212 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.61?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 16 and take away the sum of its digits. What do you get?
  23. 23.Take 12 and take away the sum of its digits. What do you get?
  24. 24.Take 71 and take away the sum of its digits. What do you get?
  25. 25.3?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.244? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?530 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 39 and take away the sum of its digits. What do you get?
  29. 29.Take 33 and take away the sum of its digits. What do you get?
  30. 30.75?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 26 and take away the sum of its digits. What do you get?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.293? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?538 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 25 and take away the sum of its digits. What do you get?
  36. 36.?503 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.728? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?389 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.8?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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