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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 324 · 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. 1.57?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 98 and take away the sum of its digits. What do you get?
  3. 3.Take 16 and take away the sum of its digits. What do you get?
  4. 4.?403 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 69 and take away the sum of its digits. What do you get?
  6. 6.17?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.823? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?896 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.209? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?158 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 93 and take away the sum of its digits. What do you get?
  12. 12.88?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.3?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 94 and take away the sum of its digits. What do you get?
  16. 16.?968 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 56 and take away the sum of its digits. What do you get?
  18. 18.6?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 32 and take away the sum of its digits. What do you get?
  20. 20.Take 64 and take away the sum of its digits. What do you get?
  21. 21.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 84 and take away the sum of its digits. What do you get?
  23. 23.Take 42 and take away the sum of its digits. What do you get?
  24. 24.Take 81 and take away the sum of its digits. What do you get?
  25. 25.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 36 and take away the sum of its digits. What do you get?
  27. 27.Take 92 and take away the sum of its digits. What do you get?
  28. 28.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?311 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 18 and take away the sum of its digits. What do you get?
  31. 31.Take 58 and take away the sum of its digits. What do you get?
  32. 32.?517 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 65 and take away the sum of its digits. What do you get?
  35. 35.?723 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 49 and take away the sum of its digits. What do you get?
  37. 37.Take 71 and take away the sum of its digits. What do you get?
  38. 38.Take 80 and take away the sum of its digits. What do you get?
  39. 39.488? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.40? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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