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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 348 · 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 51 and take away the sum of its digits. What do you get?
  2. 2.4?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 70 and take away the sum of its digits. What do you get?
  4. 4.Take 69 and take away the sum of its digits. What do you get?
  5. 5.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 11 and take away the sum of its digits. What do you get?
  7. 7.Take 28 and take away the sum of its digits. What do you get?
  8. 8.Take 61 and take away the sum of its digits. What do you get?
  9. 9.38?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 45 and take away the sum of its digits. What do you get?
  12. 12.Take 17 and take away the sum of its digits. What do you get?
  13. 13.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?659 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?857 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.21?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?735 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?663 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.579? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 29 and take away the sum of its digits. What do you get?
  22. 22.405? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?316 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 64 and take away the sum of its digits. What do you get?
  25. 25.80?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.895? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 41 and take away the sum of its digits. What do you get?
  31. 31.?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 24 and take away the sum of its digits. What do you get?
  33. 33.Take 89 and take away the sum of its digits. What do you get?
  34. 34.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 65 and take away the sum of its digits. What do you get?
  36. 36.7?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?624 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 76 and take away the sum of its digits. What do you get?
  40. 40.?790 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. 5
  3. 63
  4. 54
  5. 6
  6. 9
  7. 18
  8. 54
  9. 1
  10. 1
  11. 36
  12. 9
  13. 8
  14. 7
  15. 7
  16. 2
  17. 3
  18. 3
  19. 8
  20. 6
  21. 18
  22. 9
  23. 8
  24. 54
  25. 7
  26. 8
  27. 9
  28. 6
  29. 5
  30. 36
  31. 5
  32. 18
  33. 72
  34. 1
  35. 54
  36. 2
  37. 6
  38. 1
  39. 63
  40. 2

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