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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 409 · 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. 1.4?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.58?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.28?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?902 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.721? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.62?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.327? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 31 and take away the sum of its digits. What do you get?
  11. 11.41?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 20 and take away the sum of its digits. What do you get?
  13. 13.729? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 70 and take away the sum of its digits. What do you get?
  15. 15.5?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?4 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.Take 16 and take away the sum of its digits. What do you get?
  21. 21.?660 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 52 and take away the sum of its digits. What do you get?
  24. 24.Take 69 and take away the sum of its digits. What do you get?
  25. 25.7?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.11?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 75 and take away the sum of its digits. What do you get?
  28. 28.893? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.32?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.50?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?700 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 78 and take away the sum of its digits. What do you get?
  34. 34.?959 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?519 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.148? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.364? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.397? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.354? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 39 and take away the sum of its digits. What do you get?

Answer key

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

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