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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 34 · 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 48 and take away the sum of its digits. What do you get?
  2. 2.Take 81 and take away the sum of its digits. What do you get?
  3. 3.?357 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.22?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.533? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.88?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.174? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 45 and take away the sum of its digits. What do you get?
  14. 14.21?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?444 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 56 and take away the sum of its digits. What do you get?
  19. 19.?745 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?278 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?084 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?379 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 78 and take away the sum of its digits. What do you get?
  26. 26.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 82 and take away the sum of its digits. What do you get?
  29. 29.Take 24 and take away the sum of its digits. What do you get?
  30. 30.Take 22 and take away the sum of its digits. What do you get?
  31. 31.16?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 32 and take away the sum of its digits. What do you get?
  34. 34.?569 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.300? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.81?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?401 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 51 and take away the sum of its digits. What do you get?
  40. 40.Take 37 and take away the sum of its digits. What do you get?

Answer key

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

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