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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 303 · 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. 1.59?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.311? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.75?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?500 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 73 and take away the sum of its digits. What do you get?
  9. 9.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?807 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?926 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.21?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.3?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.370? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 35 and take away the sum of its digits. What do you get?
  17. 17.Take 82 and take away the sum of its digits. What do you get?
  18. 18.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 97 and take away the sum of its digits. What do you get?
  20. 20.Take 22 and take away the sum of its digits. What do you get?
  21. 21.Take 78 and take away the sum of its digits. What do you get?
  22. 22.579? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.56?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.79?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 84 and take away the sum of its digits. What do you get?
  26. 26.Take 56 and take away the sum of its digits. What do you get?
  27. 27.Take 49 and take away the sum of its digits. What do you get?
  28. 28.601? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 86 and take away the sum of its digits. What do you get?
  30. 30.?788 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 19 and take away the sum of its digits. What do you get?
  34. 34.?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 63 and take away the sum of its digits. What do you get?
  37. 37.871? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?641 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?519 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.1?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 7
  2. 4
  3. 3
  4. 5
  5. 7
  6. 2
  7. 4
  8. 63
  9. 2
  10. 3
  11. 1
  12. 1
  13. 2
  14. 8
  15. 8
  16. 27
  17. 72
  18. 7
  19. 81
  20. 18
  21. 63
  22. 6
  23. 7
  24. 2
  25. 72
  26. 45
  27. 36
  28. 2
  29. 72
  30. 4
  31. 8
  32. 5
  33. 9
  34. 6
  35. 3
  36. 54
  37. 2
  38. 7
  39. 3
  40. 3

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