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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 371 · 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. 1.806? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 98 and take away the sum of its digits. What do you get?
  3. 3.Take 90 and take away the sum of its digits. What do you get?
  4. 4.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 48 and take away the sum of its digits. What do you get?
  6. 6.627? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 26 and take away the sum of its digits. What do you get?
  8. 8.6?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.31?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 85 and take away the sum of its digits. What do you get?
  14. 14.64?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 51 and take away the sum of its digits. What do you get?
  19. 19.3?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?429 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 97 and take away the sum of its digits. What do you get?
  23. 23.83?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.334? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.57?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?5 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.Take 33 and take away the sum of its digits. What do you get?
  31. 31.Take 22 and take away the sum of its digits. What do you get?
  32. 32.Take 57 and take away the sum of its digits. What do you get?
  33. 33.102? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.87?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.24?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 28 and take away the sum of its digits. What do you get?
  38. 38.24? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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