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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 835 · 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.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.51?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 99 and take away the sum of its digits. What do you get?
  4. 4.75?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?431 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.?781 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.5?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.344? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.835? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 39 and take away the sum of its digits. What do you get?
  12. 12.6?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.87?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.32?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 30 and take away the sum of its digits. What do you get?
  18. 18.Take 78 and take away the sum of its digits. What do you get?
  19. 19.7?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?687 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 92 and take away the sum of its digits. What do you get?
  22. 22.Take 91 and take away the sum of its digits. What do you get?
  23. 23.462? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.9?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 68 and take away the sum of its digits. What do you get?
  26. 26.?023 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.81?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 11 and take away the sum of its digits. What do you get?
  29. 29.88?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?574 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 28 and take away the sum of its digits. What do you get?
  33. 33.?867 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.568? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 14 and take away the sum of its digits. What do you get?
  36. 36.?529 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 25 and take away the sum of its digits. What do you get?
  38. 38.Take 36 and take away the sum of its digits. What do you get?
  39. 39.?364 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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