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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 758 · 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. 1.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.4?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.7?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.5?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.578? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.850? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 75 and take away the sum of its digits. What do you get?
  8. 8.Take 40 and take away the sum of its digits. What do you get?
  9. 9.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 31 and take away the sum of its digits. What do you get?
  11. 11.Take 56 and take away the sum of its digits. What do you get?
  12. 12.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.24?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.29?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?942 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 27 and take away the sum of its digits. What do you get?
  18. 18.110? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 52 and take away the sum of its digits. What do you get?
  20. 20.81?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.32?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.684? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.19?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.406? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 36 and take away the sum of its digits. What do you get?
  26. 26.53?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 30 and take away the sum of its digits. What do you get?
  28. 28.Take 38 and take away the sum of its digits. What do you get?
  29. 29.775? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.6?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 95 and take away the sum of its digits. What do you get?
  33. 33.30?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?762 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.293? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 12 and take away the sum of its digits. What do you get?
  37. 37.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.45?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?219 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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