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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 2 · 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. 1.19?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.1?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.23?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.3?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.77?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.535? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 51 and take away the sum of its digits. What do you get?
  9. 9.130? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.704? 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.?160 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.578? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.192? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.871? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?122 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 32 and take away the sum of its digits. What do you get?
  19. 19.29? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 83 and take away the sum of its digits. What do you get?
  21. 21.Take 66 and take away the sum of its digits. What do you get?
  22. 22.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 88 and take away the sum of its digits. What do you get?
  24. 24.Take 27 and take away the sum of its digits. What do you get?
  25. 25.?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.41?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?798 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.882? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?757 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.610? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 87 and take away the sum of its digits. What do you get?
  32. 32.27?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 57 and take away the sum of its digits. What do you get?
  34. 34.Take 80 and take away the sum of its digits. What do you get?
  35. 35.4?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.22?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 58 and take away the sum of its digits. What do you get?
  38. 38.Take 11 and take away the sum of its digits. What do you get?
  39. 39.Take 22 and take away the sum of its digits. What do you get?
  40. 40.Take 67 and take away the sum of its digits. What do you get?

Answer key

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

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