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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 918 · 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. 1.88?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 26 and take away the sum of its digits. What do you get?
  3. 3.5?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 60 and take away the sum of its digits. What do you get?
  5. 5.Take 91 and take away the sum of its digits. What do you get?
  6. 6.?264 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?349 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.866? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.1?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 41 and take away the sum of its digits. What do you get?
  11. 11.Take 72 and take away the sum of its digits. What do you get?
  12. 12.6?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 70 and take away the sum of its digits. What do you get?
  14. 14.?289 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?469 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?537 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 57 and take away the sum of its digits. What do you get?
  20. 20.?496 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?434 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. 24.54?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?128 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 15 and take away the sum of its digits. What do you get?
  28. 28.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 21 and take away the sum of its digits. What do you get?
  30. 30.8?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 48 and take away the sum of its digits. What do you get?
  32. 32.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?443 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.8?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.358? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?911 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 28 and take away the sum of its digits. What do you get?
  39. 39.37?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.839? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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