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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 639 · 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.?812 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 57 and take away the sum of its digits. What do you get?
  3. 3.7?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.23?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.168? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?059 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 27 and take away the sum of its digits. What do you get?
  9. 9.Take 61 and take away the sum of its digits. What do you get?
  10. 10.573? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 83 and take away the sum of its digits. What do you get?
  12. 12.226? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.803? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.64?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.886? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 94 and take away the sum of its digits. What do you get?
  19. 19.23?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 82 and take away the sum of its digits. What do you get?
  23. 23.261? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 58 and take away the sum of its digits. What do you get?
  25. 25.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?969 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 28 and take away the sum of its digits. What do you get?
  28. 28.185? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.34?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 42 and take away the sum of its digits. What do you get?
  31. 31.Take 77 and take away the sum of its digits. What do you get?
  32. 32.?858 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.7?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?807 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 48 and take away the sum of its digits. What do you get?
  36. 36.Take 65 and take away the sum of its digits. What do you get?
  37. 37.Take 51 and take away the sum of its digits. What do you get?
  38. 38.?805 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.8?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 20 and take away the sum of its digits. What do you get?

Answer key

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

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