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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 414 · 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. 1.17?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.66?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 25 and take away the sum of its digits. What do you get?
  4. 4.Take 20 and take away the sum of its digits. What do you get?
  5. 5.79?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 16 and take away the sum of its digits. What do you get?
  7. 7.Take 77 and take away the sum of its digits. What do you get?
  8. 8.563? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.119? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.429? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.503? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 41 and take away the sum of its digits. What do you get?
  14. 14.2?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 18 and take away the sum of its digits. What do you get?
  16. 16.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?528 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.82?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.4?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.26?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.44?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?664 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.392? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.328? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.87?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?123 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 98 and take away the sum of its digits. What do you get?
  34. 34.140? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.37?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.300? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 63 and take away the sum of its digits. What do you get?
  38. 38.343? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.5?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?404 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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