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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 44 · 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 56 and take away the sum of its digits. What do you get?
  2. 2.Take 65 and take away the sum of its digits. What do you get?
  3. 3.Take 59 and take away the sum of its digits. What do you get?
  4. 4.43?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.34?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 50 and take away the sum of its digits. What do you get?
  8. 8.Take 39 and take away the sum of its digits. What do you get?
  9. 9.?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.40? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.72?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.476? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.78?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.357? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 89 and take away the sum of its digits. What do you get?
  16. 16.859? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?124 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.4?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.19?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 51 and take away the sum of its digits. What do you get?
  21. 21.Take 84 and take away the sum of its digits. What do you get?
  22. 22.?136 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 30 and take away the sum of its digits. What do you get?
  24. 24.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.400? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 24 and take away the sum of its digits. What do you get?
  28. 28.1?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 97 and take away the sum of its digits. What do you get?
  30. 30.620? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.79?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 22 and take away the sum of its digits. What do you get?
  33. 33.?875 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 73 and take away the sum of its digits. What do you get?
  35. 35.793? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?498 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 64 and take away the sum of its digits. What do you get?
  39. 39.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.9?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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