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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 152 · 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. 1.843? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 31 and take away the sum of its digits. What do you get?
  3. 3.Take 72 and take away the sum of its digits. What do you get?
  4. 4.6?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.6?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 32 and take away the sum of its digits. What do you get?
  7. 7.5?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.1?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?382 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.390? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.97? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 66 and take away the sum of its digits. What do you get?
  13. 13.6?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 11 and take away the sum of its digits. What do you get?
  15. 15.Take 50 and take away the sum of its digits. What do you get?
  16. 16.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.656? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 92 and take away the sum of its digits. What do you get?
  19. 19.?199 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?992 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?229 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 80 and take away the sum of its digits. What do you get?
  26. 26.73?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 75 and take away the sum of its digits. What do you get?
  28. 28.6?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 34 and take away the sum of its digits. What do you get?
  30. 30.635? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 14 and take away the sum of its digits. What do you get?
  33. 33.3?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.272? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.41?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.135? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?997 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. 27
  3. 63
  4. 5
  5. 9
  6. 27
  7. 7
  8. 7
  9. 5
  10. 6
  11. 2
  12. 54
  13. 9
  14. 9
  15. 45
  16. 1
  17. 1
  18. 81
  19. 8
  20. 2
  21. 7
  22. 5
  23. 6
  24. 1
  25. 72
  26. 1
  27. 63
  28. 7
  29. 27
  30. 4
  31. 9
  32. 9
  33. 8
  34. 5
  35. 7
  36. 2
  37. 3
  38. 9
  39. 2
  40. 2

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