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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 342 · 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 99 and take away the sum of its digits. What do you get?
  2. 2.4?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 12 and take away the sum of its digits. What do you get?
  4. 4.186? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 34 and take away the sum of its digits. What do you get?
  6. 6.4?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 93 and take away the sum of its digits. What do you get?
  8. 8.3?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?097 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.66?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.55?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?061 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.472? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 37 and take away the sum of its digits. What do you get?
  17. 17.181? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 44 and take away the sum of its digits. What do you get?
  19. 19.357? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 42 and take away the sum of its digits. What do you get?
  21. 21.19? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.464? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 36 and take away the sum of its digits. What do you get?
  26. 26.54?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.53?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?836 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 77 and take away the sum of its digits. What do you get?
  30. 30.Take 80 and take away the sum of its digits. What do you get?
  31. 31.Take 41 and take away the sum of its digits. What do you get?
  32. 32.Take 84 and take away the sum of its digits. What do you get?
  33. 33.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.474? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 31 and take away the sum of its digits. What do you get?
  38. 38.Take 51 and take away the sum of its digits. What do you get?
  39. 39.894? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.11?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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