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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 121 · 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 62 and take away the sum of its digits. What do you get?
  2. 2.Take 42 and take away the sum of its digits. What do you get?
  3. 3.Take 39 and take away the sum of its digits. What do you get?
  4. 4.Take 71 and take away the sum of its digits. What do you get?
  5. 5.357? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?361 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.831? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 81 and take away the sum of its digits. What do you get?
  9. 9.135? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.684? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 16 and take away the sum of its digits. What do you get?
  12. 12.?877 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.75?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 38 and take away the sum of its digits. What do you get?
  15. 15.Take 44 and take away the sum of its digits. What do you get?
  16. 16.Take 92 and take away the sum of its digits. What do you get?
  17. 17.129? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 30 and take away the sum of its digits. What do you get?
  19. 19.Take 75 and take away the sum of its digits. What do you get?
  20. 20.61?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.656? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?021 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.53?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 50 and take away the sum of its digits. What do you get?
  26. 26.Take 79 and take away the sum of its digits. What do you get?
  27. 27.Take 27 and take away the sum of its digits. What do you get?
  28. 28.6?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.59?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.14?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.43?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 68 and take away the sum of its digits. What do you get?
  34. 34.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 51 and take away the sum of its digits. What do you get?
  36. 36.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 80 and take away the sum of its digits. What do you get?
  38. 38.804? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?316 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?061 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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