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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 198 · 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 90 and take away the sum of its digits. What do you get?
  2. 2.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.563? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.6?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 80 and take away the sum of its digits. What do you get?
  7. 7.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 27 and take away the sum of its digits. What do you get?
  9. 9.Take 44 and take away the sum of its digits. What do you get?
  10. 10.?946 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.206? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?598 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?025 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.24? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.4?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 87 and take away the sum of its digits. What do you get?
  19. 19.190? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?011 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?286 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.16?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 82 and take away the sum of its digits. What do you get?
  24. 24.8?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?715 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.785? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.879? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 46 and take away the sum of its digits. What do you get?
  29. 29.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 63 and take away the sum of its digits. What do you get?
  31. 31.Take 41 and take away the sum of its digits. What do you get?
  32. 32.Take 86 and take away the sum of its digits. What do you get?
  33. 33.?446 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.74?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 22 and take away the sum of its digits. What do you get?
  36. 36.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.30?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.557? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 81
  2. 9
  3. 4
  4. 5
  5. 7
  6. 72
  7. 1
  8. 18
  9. 36
  10. 8
  11. 1
  12. 5
  13. 5
  14. 2
  15. 3
  16. 9
  17. 1
  18. 72
  19. 8
  20. 7
  21. 2
  22. 2
  23. 72
  24. 7
  25. 5
  26. 7
  27. 3
  28. 36
  29. 7
  30. 54
  31. 36
  32. 72
  33. 4
  34. 9
  35. 18
  36. 1
  37. 4
  38. 1
  39. 1
  40. 3

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