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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 595 · 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 36 and take away the sum of its digits. What do you get?
  2. 2.86?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?359 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 57 and take away the sum of its digits. What do you get?
  6. 6.Take 83 and take away the sum of its digits. What do you get?
  7. 7.5?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 71 and take away the sum of its digits. What do you get?
  9. 9.?085 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.794? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.8?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.136? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.50?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?368 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?979 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?479 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?665 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 62 and take away the sum of its digits. What do you get?
  21. 21.Take 40 and take away the sum of its digits. What do you get?
  22. 22.856? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.8?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.127? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?921 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.62?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.31? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 51 and take away the sum of its digits. What do you get?
  30. 30.Take 19 and take away the sum of its digits. What do you get?
  31. 31.Take 88 and take away the sum of its digits. What do you get?
  32. 32.Take 32 and take away the sum of its digits. What do you get?
  33. 33.89?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.40?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?700 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 18 and take away the sum of its digits. What do you get?
  38. 38.Take 17 and take away the sum of its digits. What do you get?
  39. 39.15?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 99 and take away the sum of its digits. What do you get?

Answer key

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

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