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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 904 · 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. 1.1?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?988 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 21 and take away the sum of its digits. What do you get?
  4. 4.?596 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 38 and take away the sum of its digits. What do you get?
  6. 6.Take 75 and take away the sum of its digits. What do you get?
  7. 7.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 25 and take away the sum of its digits. What do you get?
  9. 9.3?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?206 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 80 and take away the sum of its digits. What do you get?
  12. 12.?200 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.219? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 32 and take away the sum of its digits. What do you get?
  15. 15.Take 67 and take away the sum of its digits. What do you get?
  16. 16.490? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 49 and take away the sum of its digits. What do you get?
  18. 18.Take 37 and take away the sum of its digits. What do you get?
  19. 19.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?814 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?403 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 43 and take away the sum of its digits. What do you get?
  24. 24.541? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 39 and take away the sum of its digits. What do you get?
  26. 26.82?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 53 and take away the sum of its digits. What do you get?
  29. 29.414? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.709? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?811 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.72?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.8?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?168 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 98 and take away the sum of its digits. What do you get?
  37. 37.1?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?921 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 47 and take away the sum of its digits. What do you get?
  40. 40.Take 17 and take away the sum of its digits. What do you get?

Answer key

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

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