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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 96 · 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. 1.6?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 28 and take away the sum of its digits. What do you get?
  3. 3.26?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?695 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 71 and take away the sum of its digits. What do you get?
  6. 6.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.4?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.699? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.18?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?894 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 88 and take away the sum of its digits. What do you get?
  12. 12.4?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?660 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 50 and take away the sum of its digits. What do you get?
  16. 16.Take 78 and take away the sum of its digits. What do you get?
  17. 17.Take 30 and take away the sum of its digits. What do you get?
  18. 18.?646 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.587? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.56?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.44?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?037 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 15 and take away the sum of its digits. What do you get?
  26. 26.305? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 79 and take away the sum of its digits. What do you get?
  28. 28.Take 80 and take away the sum of its digits. What do you get?
  29. 29.Take 34 and take away the sum of its digits. What do you get?
  30. 30.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?080 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?497 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 61 and take away the sum of its digits. What do you get?
  34. 34.?948 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.576? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 42 and take away the sum of its digits. What do you get?
  38. 38.Take 54 and take away the sum of its digits. What do you get?
  39. 39.Take 91 and take away the sum of its digits. What do you get?
  40. 40.71?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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