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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 843 · 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.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 76 and take away the sum of its digits. What do you get?
  3. 3.Take 89 and take away the sum of its digits. What do you get?
  4. 4.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.30?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 36 and take away the sum of its digits. What do you get?
  7. 7.?570 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.45?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?953 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.3?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?760 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.5?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 88 and take away the sum of its digits. What do you get?
  14. 14.Take 51 and take away the sum of its digits. What do you get?
  15. 15.163? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.25?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?663 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 13 and take away the sum of its digits. What do you get?
  19. 19.Take 43 and take away the sum of its digits. What do you get?
  20. 20.862? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.49?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 59 and take away the sum of its digits. What do you get?
  27. 27.2?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 83 and take away the sum of its digits. What do you get?
  29. 29.39?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?714 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?280 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.61?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.528? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.3?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?337 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.169? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.530? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.29?7 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. 63
  3. 72
  4. 5
  5. 3
  6. 27
  7. 6
  8. 9
  9. 1
  10. 6
  11. 5
  12. 2
  13. 72
  14. 45
  15. 8
  16. 2
  17. 3
  18. 9
  19. 36
  20. 2
  21. 2
  22. 2
  23. 3
  24. 5
  25. 5
  26. 45
  27. 3
  28. 72
  29. 2
  30. 6
  31. 6
  32. 8
  33. 7
  34. 3
  35. 4
  36. 5
  37. 4
  38. 2
  39. 1
  40. 9

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