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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 601 · 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.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 51 and take away the sum of its digits. What do you get?
  3. 3.Take 39 and take away the sum of its digits. What do you get?
  4. 4.834? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 95 and take away the sum of its digits. What do you get?
  7. 7.Take 67 and take away the sum of its digits. What do you get?
  8. 8.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.5?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 33 and take away the sum of its digits. What do you get?
  11. 11.?320 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 17 and take away the sum of its digits. What do you get?
  13. 13.6?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.574? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.799? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.1?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.17? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 26 and take away the sum of its digits. What do you get?
  24. 24.Take 78 and take away the sum of its digits. What do you get?
  25. 25.?080 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.839? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 24 and take away the sum of its digits. What do you get?
  31. 31.166? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.297? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 47 and take away the sum of its digits. What do you get?
  34. 34.?566 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.529? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 23 and take away the sum of its digits. What do you get?
  37. 37.86?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 91 and take away the sum of its digits. What do you get?
  39. 39.18?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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