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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 150 · 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. 1.82?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 19 and take away the sum of its digits. What do you get?
  3. 3.Take 16 and take away the sum of its digits. What do you get?
  4. 4.9?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 25 and take away the sum of its digits. What do you get?
  7. 7.Take 58 and take away the sum of its digits. What do you get?
  8. 8.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 22 and take away the sum of its digits. What do you get?
  11. 11.523? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 81 and take away the sum of its digits. What do you get?
  13. 13.47?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.74?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 21 and take away the sum of its digits. What do you get?
  16. 16.?907 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 87 and take away the sum of its digits. What do you get?
  18. 18.Take 75 and take away the sum of its digits. What do you get?
  19. 19.62?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 24 and take away the sum of its digits. What do you get?
  21. 21.Take 94 and take away the sum of its digits. What do you get?
  22. 22.10?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.375? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.43?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?822 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.19? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.820? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.41?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 27 and take away the sum of its digits. What do you get?
  31. 31.?871 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?334 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.69?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.861? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 26 and take away the sum of its digits. What do you get?
  36. 36.5?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 70 and take away the sum of its digits. What do you get?
  38. 38.?309 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.74?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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