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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 538 · 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 94 and take away the sum of its digits. What do you get?
  2. 2.Take 85 and take away the sum of its digits. What do you get?
  3. 3.525? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.2?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 20 and take away the sum of its digits. What do you get?
  6. 6.20?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.299? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 51 and take away the sum of its digits. What do you get?
  10. 10.2?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 93 and take away the sum of its digits. What do you get?
  12. 12.608? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 25 and take away the sum of its digits. What do you get?
  14. 14.Take 30 and take away the sum of its digits. What do you get?
  15. 15.Take 57 and take away the sum of its digits. What do you get?
  16. 16.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.526? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.393? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.62? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.4?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 97 and take away the sum of its digits. What do you get?
  23. 23.?211 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 53 and take away the sum of its digits. What do you get?
  25. 25.613? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 58 and take away the sum of its digits. What do you get?
  27. 27.Take 66 and take away the sum of its digits. What do you get?
  28. 28.Take 77 and take away the sum of its digits. What do you get?
  29. 29.Take 49 and take away the sum of its digits. What do you get?
  30. 30.?245 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.88?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?156 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 82 and take away the sum of its digits. What do you get?
  34. 34.?885 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?894 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?694 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?353 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.2?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.843? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 47 and take away the sum of its digits. What do you get?

Answer key

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

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