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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 552 · 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. 1.37?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 83 and take away the sum of its digits. What do you get?
  3. 3.Take 19 and take away the sum of its digits. What do you get?
  4. 4.8?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.606? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.80?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 69 and take away the sum of its digits. What do you get?
  10. 10.6?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 74 and take away the sum of its digits. What do you get?
  12. 12.Take 14 and take away the sum of its digits. What do you get?
  13. 13.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.5?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?299 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?200 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 36 and take away the sum of its digits. What do you get?
  21. 21.Take 53 and take away the sum of its digits. What do you get?
  22. 22.Take 47 and take away the sum of its digits. What do you get?
  23. 23.Take 60 and take away the sum of its digits. What do you get?
  24. 24.Take 99 and take away the sum of its digits. What do you get?
  25. 25.Take 95 and take away the sum of its digits. What do you get?
  26. 26.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 41 and take away the sum of its digits. What do you get?
  28. 28.?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?024 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.73?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.41?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?553 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.62?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 42 and take away the sum of its digits. What do you get?
  36. 36.355? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.480? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 54 and take away the sum of its digits. What do you get?
  39. 39.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.79?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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