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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 230 · 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. 1.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 95 and take away the sum of its digits. What do you get?
  4. 4.Take 22 and take away the sum of its digits. What do you get?
  5. 5.Take 73 and take away the sum of its digits. What do you get?
  6. 6.Take 39 and take away the sum of its digits. What do you get?
  7. 7.Take 28 and take away the sum of its digits. What do you get?
  8. 8.821? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 13 and take away the sum of its digits. What do you get?
  10. 10.?835 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.333? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.109? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 92 and take away the sum of its digits. What do you get?
  15. 15.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.73?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?055 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.328? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.657? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.744? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?409 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?096 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 99 and take away the sum of its digits. What do you get?
  24. 24.?767 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 78 and take away the sum of its digits. What do you get?
  30. 30.Take 16 and take away the sum of its digits. What do you get?
  31. 31.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 21 and take away the sum of its digits. What do you get?
  33. 33.726? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 24 and take away the sum of its digits. What do you get?
  35. 35.?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?142 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 27 and take away the sum of its digits. What do you get?
  40. 40.Take 93 and take away the sum of its digits. What do you get?

Answer key

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

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