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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 235 · 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 65 and take away the sum of its digits. What do you get?
  2. 2.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.6?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 36 and take away the sum of its digits. What do you get?
  5. 5.43?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.8?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 24 and take away the sum of its digits. What do you get?
  8. 8.?317 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.86?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.3?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.60?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 14 and take away the sum of its digits. What do you get?
  14. 14.5?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 13 and take away the sum of its digits. What do you get?
  16. 16.?402 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 69 and take away the sum of its digits. What do you get?
  18. 18.4?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 27 and take away the sum of its digits. What do you get?
  20. 20.69?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 54 and take away the sum of its digits. What do you get?
  22. 22.2?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.81?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 16 and take away the sum of its digits. What do you get?
  25. 25.?691 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?759 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 64 and take away the sum of its digits. What do you get?
  28. 28.150? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.14?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.7?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.87?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 71 and take away the sum of its digits. What do you get?
  33. 33.Take 97 and take away the sum of its digits. What do you get?
  34. 34.Take 78 and take away the sum of its digits. What do you get?
  35. 35.4?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.107? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?742 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?471 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.373? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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