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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 819 · 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. 1.5?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.78?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 60 and take away the sum of its digits. What do you get?
  6. 6.794? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?431 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 23 and take away the sum of its digits. What do you get?
  10. 10.86?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.148? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?532 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 14 and take away the sum of its digits. What do you get?
  16. 16.137? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?984 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.555? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 90 and take away the sum of its digits. What do you get?
  23. 23.8?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 29 and take away the sum of its digits. What do you get?
  25. 25.Take 85 and take away the sum of its digits. What do you get?
  26. 26.562? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 55 and take away the sum of its digits. What do you get?
  28. 28.?240 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?181 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 98 and take away the sum of its digits. What do you get?
  31. 31.?664 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.40?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?325 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.12?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 71 and take away the sum of its digits. What do you get?
  37. 37.Take 30 and take away the sum of its digits. What do you get?
  38. 38.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?732 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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