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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 307 · 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. 1.8?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.509? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 65 and take away the sum of its digits. What do you get?
  4. 4.4?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.3?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?461 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.1?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 95 and take away the sum of its digits. What do you get?
  12. 12.?636 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.224? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 33 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. 16.79?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.179? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?761 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?753 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.449? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 13 and take away the sum of its digits. What do you get?
  23. 23.?678 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?190 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.3?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?492 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.42?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 47 and take away the sum of its digits. What do you get?
  30. 30.?861 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.4?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 98 and take away the sum of its digits. What do you get?
  34. 34.35?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 35 and take away the sum of its digits. What do you get?
  38. 38.99? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?694 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. 4
  3. 54
  4. 1
  5. 1
  6. 9
  7. 7
  8. 2
  9. 7
  10. 7
  11. 81
  12. 3
  13. 1
  14. 27
  15. 54
  16. 2
  17. 1
  18. 4
  19. 3
  20. 1
  21. 4
  22. 9
  23. 6
  24. 8
  25. 5
  26. 3
  27. 1
  28. 5
  29. 36
  30. 3
  31. 2
  32. 3
  33. 81
  34. 1
  35. 2
  36. 5
  37. 27
  38. 9
  39. 1
  40. 8

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