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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 809 · 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. 1.77?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.55?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 32 and take away the sum of its digits. What do you get?
  5. 5.Take 95 and take away the sum of its digits. What do you get?
  6. 6.8?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?696 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.23? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?547 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.12?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.6?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.151? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.48?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 75 and take away the sum of its digits. What do you get?
  18. 18.Take 61 and take away the sum of its digits. What do you get?
  19. 19.Take 18 and take away the sum of its digits. What do you get?
  20. 20.Take 20 and take away the sum of its digits. What do you get?
  21. 21.152? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 13 and take away the sum of its digits. What do you get?
  23. 23.Take 67 and take away the sum of its digits. What do you get?
  24. 24.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?247 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?206 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.7?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 17 and take away the sum of its digits. What do you get?
  29. 29.2?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 50 and take away the sum of its digits. What do you get?
  31. 31.Take 36 and take away the sum of its digits. What do you get?
  32. 32.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.756? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 34 and take away the sum of its digits. What do you get?
  35. 35.Take 54 and take away the sum of its digits. What do you get?
  36. 36.Take 64 and take away the sum of its digits. What do you get?
  37. 37.1?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 52 and take away the sum of its digits. What do you get?
  39. 39.79? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.49?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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