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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 309 · 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.?190 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.42?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?897 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?818 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 36 and take away the sum of its digits. What do you get?
  7. 7.528? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 97 and take away the sum of its digits. What do you get?
  10. 10.Take 44 and take away the sum of its digits. What do you get?
  11. 11.713? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.28?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 46 and take away the sum of its digits. What do you get?
  14. 14.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.53?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?480 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 85 and take away the sum of its digits. What do you get?
  18. 18.Take 70 and take away the sum of its digits. What do you get?
  19. 19.5?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.77?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.479? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.272? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 37 and take away the sum of its digits. What do you get?
  27. 27.Take 14 and take away the sum of its digits. What do you get?
  28. 28.4?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.231? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 50 and take away the sum of its digits. What do you get?
  31. 31.?745 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 39 and take away the sum of its digits. What do you get?
  33. 33.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?039 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?298 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?581 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.8?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?969 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 81 and take away the sum of its digits. What do you get?

Answer key

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

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