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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 135 · 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. 1.209? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 54 and take away the sum of its digits. What do you get?
  3. 3.12?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.832? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?768 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.570? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.7?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 21 and take away the sum of its digits. What do you get?
  11. 11.60?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 23 and take away the sum of its digits. What do you get?
  15. 15.8?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 86 and take away the sum of its digits. What do you get?
  19. 19.53?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.85?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.42?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?012 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 80 and take away the sum of its digits. What do you get?
  26. 26.Take 62 and take away the sum of its digits. What do you get?
  27. 27.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?899 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.444? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 91 and take away the sum of its digits. What do you get?
  32. 32.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?163 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.1?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 60 and take away the sum of its digits. What do you get?
  37. 37.Take 32 and take away the sum of its digits. What do you get?
  38. 38.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.4?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.9?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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