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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 855 · 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 11 and take away the sum of its digits. What do you get?
  2. 2.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 20 and take away the sum of its digits. What do you get?
  4. 4.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.8?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.6?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.358? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 79 and take away the sum of its digits. What do you get?
  10. 10.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 51 and take away the sum of its digits. What do you get?
  12. 12.529? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?728 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.4?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 19 and take away the sum of its digits. What do you get?
  16. 16.?969 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.241? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.71?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?010 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 18 and take away the sum of its digits. What do you get?
  23. 23.41?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.5?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?082 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 84 and take away the sum of its digits. What do you get?
  28. 28.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.301? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 80 and take away the sum of its digits. What do you get?
  31. 31.?539 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.709? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 87 and take away the sum of its digits. What do you get?
  34. 34.Take 86 and take away the sum of its digits. What do you get?
  35. 35.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 58 and take away the sum of its digits. What do you get?
  37. 37.15?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.718? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 95 and take away the sum of its digits. What do you get?
  40. 40.Take 29 and take away the sum of its digits. What do you get?

Answer key

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

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