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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 914 · 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.?818 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.715? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 37 and take away the sum of its digits. What do you get?
  5. 5.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 22 and take away the sum of its digits. What do you get?
  7. 7.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?427 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?152 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.110? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 41 and take away the sum of its digits. What do you get?
  13. 13.Take 87 and take away the sum of its digits. What do you get?
  14. 14.Take 73 and take away the sum of its digits. What do you get?
  15. 15.876? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 39 and take away the sum of its digits. What do you get?
  17. 17.Take 79 and take away the sum of its digits. What do you get?
  18. 18.Take 81 and take away the sum of its digits. What do you get?
  19. 19.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.69?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.5?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 40 and take away the sum of its digits. What do you get?
  24. 24.415? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 47 and take away the sum of its digits. What do you get?
  26. 26.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 34 and take away the sum of its digits. What do you get?
  28. 28.?493 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 11 and take away the sum of its digits. What do you get?
  30. 30.5?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.688? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 91 and take away the sum of its digits. What do you get?
  33. 33.17?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.12?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.61? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?425 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?374 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.4?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 75 and take away the sum of its digits. What do you get?

Answer key

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

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