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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 368 · 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 80 and take away the sum of its digits. What do you get?
  2. 2.142? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.896? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?562 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 84 and take away the sum of its digits. What do you get?
  6. 6.Take 24 and take away the sum of its digits. What do you get?
  7. 7.?475 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.3?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.49?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 18 and take away the sum of its digits. What do you get?
  11. 11.Take 14 and take away the sum of its digits. What do you get?
  12. 12.Take 83 and take away the sum of its digits. What do you get?
  13. 13.Take 25 and take away the sum of its digits. What do you get?
  14. 14.Take 33 and take away the sum of its digits. What do you get?
  15. 15.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 69 and take away the sum of its digits. What do you get?
  17. 17.Take 91 and take away the sum of its digits. What do you get?
  18. 18.515? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.19? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 96 and take away the sum of its digits. What do you get?
  21. 21.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.29?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.62?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.766? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.332? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.40?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 58 and take away the sum of its digits. What do you get?
  31. 31.5?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.740? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 92 and take away the sum of its digits. What do you get?
  34. 34.Take 12 and take away the sum of its digits. What do you get?
  35. 35.7?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?175 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.3?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 54 and take away the sum of its digits. What do you get?
  40. 40.Take 15 and take away the sum of its digits. What do you get?

Answer key

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

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