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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 201 · 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 75 and take away the sum of its digits. What do you get?
  2. 2.1?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 99 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.Take 28 and take away the sum of its digits. What do you get?
  6. 6.Take 30 and take away the sum of its digits. What do you get?
  7. 7.?376 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.46?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.80?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.81?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 17 and take away the sum of its digits. What do you get?
  14. 14.?240 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 32 and take away the sum of its digits. What do you get?
  16. 16.17?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?515 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.650? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.21?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 22 and take away the sum of its digits. What do you get?
  21. 21.Take 89 and take away the sum of its digits. What do you get?
  22. 22.?699 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.634? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 71 and take away the sum of its digits. What do you get?
  25. 25.1?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.6?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.7?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.40?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.718? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 40 and take away the sum of its digits. What do you get?
  32. 32.?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?212 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?901 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.590? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.206? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.265? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 78 and take away the sum of its digits. What do you get?

Answer key

  1. 63
  2. 9
  3. 81
  4. 18
  5. 18
  6. 27
  7. 2
  8. 2
  9. 6
  10. 3
  11. 4
  12. 6
  13. 9
  14. 3
  15. 27
  16. 1
  17. 7
  18. 7
  19. 8
  20. 18
  21. 72
  22. 3
  23. 5
  24. 63
  25. 6
  26. 6
  27. 5
  28. 3
  29. 2
  30. 2
  31. 36
  32. 6
  33. 4
  34. 9
  35. 8
  36. 4
  37. 1
  38. 5
  39. 4
  40. 63

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