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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 72 · 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. 1.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 34 and take away the sum of its digits. What do you get?
  3. 3.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.82?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 83 and take away the sum of its digits. What do you get?
  7. 7.Take 67 and take away the sum of its digits. What do you get?
  8. 8.?193 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?215 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 99 and take away the sum of its digits. What do you get?
  12. 12.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 54 and take away the sum of its digits. What do you get?
  14. 14.5?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?766 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?659 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.562? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 11 and take away the sum of its digits. What do you get?
  23. 23.330? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 39 and take away the sum of its digits. What do you get?
  25. 25.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.67?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 40 and take away the sum of its digits. What do you get?
  28. 28.8?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.807? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 25 and take away the sum of its digits. What do you get?
  35. 35.76?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 38 and take away the sum of its digits. What do you get?
  37. 37.75?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 79 and take away the sum of its digits. What do you get?
  39. 39.405? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 30 and take away the sum of its digits. What do you get?

Answer key

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

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