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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 534 · 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 18 and take away the sum of its digits. What do you get?
  2. 2.5?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 44 and take away the sum of its digits. What do you get?
  4. 4.Take 11 and take away the sum of its digits. What do you get?
  5. 5.?435 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 45 and take away the sum of its digits. What do you get?
  9. 9.?566 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.6?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?592 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.609? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.92? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.635? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 96 and take away the sum of its digits. What do you get?
  18. 18.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 54 and take away the sum of its digits. What do you get?
  20. 20.?887 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 35 and take away the sum of its digits. What do you get?
  22. 22.83?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.37?5 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. 26.60?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.748? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 23 and take away the sum of its digits. What do you get?
  30. 30.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.590? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 94 and take away the sum of its digits. What do you get?
  33. 33.Take 90 and take away the sum of its digits. What do you get?
  34. 34.Take 95 and take away the sum of its digits. What do you get?
  35. 35.?601 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.177? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.736? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.39?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.302? 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. 9
  3. 36
  4. 9
  5. 6
  6. 8
  7. 3
  8. 36
  9. 1
  10. 9
  11. 6
  12. 1
  13. 2
  14. 3
  15. 7
  16. 4
  17. 81
  18. 5
  19. 45
  20. 4
  21. 27
  22. 3
  23. 9
  24. 3
  25. 72
  26. 2
  27. 8
  28. 8
  29. 18
  30. 9
  31. 4
  32. 81
  33. 81
  34. 81
  35. 2
  36. 3
  37. 2
  38. 5
  39. 7
  40. 4

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