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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 300 · 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. 1.42?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.3?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?845 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?985 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.5?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?340 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?037 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.52?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?822 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 85 and take away the sum of its digits. What do you get?
  13. 13.Take 12 and take away the sum of its digits. What do you get?
  14. 14.4?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 84 and take away the sum of its digits. What do you get?
  16. 16.Take 11 and take away the sum of its digits. What do you get?
  17. 17.871? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 91 and take away the sum of its digits. What do you get?
  19. 19.486? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.60?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.4?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.431? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.68?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?982 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?991 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 62 and take away the sum of its digits. What do you get?
  28. 28.74?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.89?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 18 and take away the sum of its digits. What do you get?
  31. 31.Take 44 and take away the sum of its digits. What do you get?
  32. 32.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.799? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 90 and take away the sum of its digits. What do you get?
  36. 36.3?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.182? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.4?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 94 and take away the sum of its digits. What do you get?
  40. 40.31?6 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. 2
  3. 1
  4. 5
  5. 5
  6. 2
  7. 8
  8. 8
  9. 4
  10. 2
  11. 6
  12. 72
  13. 9
  14. 5
  15. 72
  16. 9
  17. 2
  18. 81
  19. 9
  20. 9
  21. 9
  22. 2
  23. 1
  24. 8
  25. 8
  26. 8
  27. 54
  28. 3
  29. 9
  30. 9
  31. 36
  32. 5
  33. 2
  34. 2
  35. 81
  36. 6
  37. 7
  38. 7
  39. 81
  40. 8

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