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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 46 · 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.?150 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.39?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.87?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.512? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.156? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.7?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?701 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?408 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 88 and take away the sum of its digits. What do you get?
  12. 12.?956 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 20 and take away the sum of its digits. What do you get?
  14. 14.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.78?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 93 and take away the sum of its digits. What do you get?
  17. 17.?806 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 70 and take away the sum of its digits. What do you get?
  19. 19.4?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 25 and take away the sum of its digits. What do you get?
  21. 21.Take 69 and take away the sum of its digits. What do you get?
  22. 22.?99 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.?235 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 27 and take away the sum of its digits. What do you get?
  26. 26.524? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 67 and take away the sum of its digits. What do you get?
  28. 28.2?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?515 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.6?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 57 and take away the sum of its digits. What do you get?
  32. 32.Take 31 and take away the sum of its digits. What do you get?
  33. 33.Take 89 and take away the sum of its digits. What do you get?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?246 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.34?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 28 and take away the sum of its digits. What do you get?
  39. 39.Take 21 and take away the sum of its digits. What do you get?
  40. 40.10?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 1
  3. 9
  4. 1
  5. 7
  6. 6
  7. 5
  8. 2
  9. 1
  10. 6
  11. 72
  12. 7
  13. 18
  14. 5
  15. 5
  16. 81
  17. 4
  18. 63
  19. 8
  20. 18
  21. 54
  22. 9
  23. 72
  24. 8
  25. 18
  26. 7
  27. 54
  28. 1
  29. 7
  30. 3
  31. 45
  32. 27
  33. 72
  34. 45
  35. 3
  36. 6
  37. 9
  38. 18
  39. 18
  40. 8

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