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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 973 · 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 90 and take away the sum of its digits. What do you get?
  2. 2.293? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 24 and take away the sum of its digits. What do you get?
  4. 4.Take 47 and take away the sum of its digits. What do you get?
  5. 5.78?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.3?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.671? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.3?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.71?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 59 and take away the sum of its digits. What do you get?
  12. 12.Take 65 and take away the sum of its digits. What do you get?
  13. 13.Take 26 and take away the sum of its digits. What do you get?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.2?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.127? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?309 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.43?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 40 and take away the sum of its digits. What do you get?
  20. 20.1?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 42 and take away the sum of its digits. What do you get?
  22. 22.?454 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.760? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.279? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.822? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 62 and take away the sum of its digits. What do you get?
  27. 27.?821 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?275 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.54?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 14 and take away the sum of its digits. What do you get?
  31. 31.?866 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.119? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 98 and take away the sum of its digits. What do you get?
  36. 36.39?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.555? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 32 and take away the sum of its digits. What do you get?
  39. 39.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.607? 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. 4
  3. 18
  4. 36
  5. 4
  6. 4
  7. 4
  8. 7
  9. 2
  10. 7
  11. 45
  12. 54
  13. 18
  14. 27
  15. 5
  16. 8
  17. 6
  18. 2
  19. 36
  20. 2
  21. 36
  22. 5
  23. 5
  24. 9
  25. 6
  26. 54
  27. 7
  28. 4
  29. 9
  30. 9
  31. 7
  32. 2
  33. 9
  34. 7
  35. 81
  36. 3
  37. 3
  38. 27
  39. 4
  40. 5

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