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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 289 · 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. 1.771? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?940 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 53 and take away the sum of its digits. What do you get?
  4. 4.Take 92 and take away the sum of its digits. What do you get?
  5. 5.?559 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 33 and take away the sum of its digits. What do you get?
  8. 8.438? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?991 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.14?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 84 and take away the sum of its digits. What do you get?
  16. 16.Take 63 and take away the sum of its digits. What do you get?
  17. 17.Take 85 and take away the sum of its digits. What do you get?
  18. 18.2?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 27 and take away the sum of its digits. What do you get?
  20. 20.?218 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.894? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 25 and take away the sum of its digits. What do you get?
  23. 23.Take 23 and take away the sum of its digits. What do you get?
  24. 24.35?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 82 and take away the sum of its digits. What do you get?
  26. 26.84?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 12 and take away the sum of its digits. What do you get?
  28. 28.85?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 94 and take away the sum of its digits. What do you get?
  30. 30.85?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.80?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.60?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?512 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?989 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 95 and take away the sum of its digits. What do you get?
  38. 38.22?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 31 and take away the sum of its digits. What do you get?
  40. 40.?104 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. 5
  3. 45
  4. 81
  5. 8
  6. 3
  7. 27
  8. 3
  9. 3
  10. 18
  11. 1
  12. 8
  13. 4
  14. 2
  15. 72
  16. 54
  17. 72
  18. 5
  19. 18
  20. 7
  21. 6
  22. 18
  23. 18
  24. 8
  25. 72
  26. 6
  27. 9
  28. 8
  29. 81
  30. 3
  31. 1
  32. 3
  33. 7
  34. 4
  35. 1
  36. 1
  37. 81
  38. 3
  39. 27
  40. 4

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