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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 165 · 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. 1.19?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.324? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 96 and take away the sum of its digits. What do you get?
  4. 4.Take 34 and take away the sum of its digits. What do you get?
  5. 5.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.789? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.46?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.2?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?719 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.68?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.2?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.31?2 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 90 and take away the sum of its digits. What do you get?
  16. 16.?269 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 17 and take away the sum of its digits. What do you get?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.Take 39 and take away the sum of its digits. What do you get?
  20. 20.?965 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.2?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.646? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 76 and take away the sum of its digits. What do you get?
  25. 25.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 97 and take away the sum of its digits. What do you get?
  27. 27.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 25 and take away the sum of its digits. What do you get?
  29. 29.Take 80 and take away the sum of its digits. What do you get?
  30. 30.17?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 31 and take away the sum of its digits. What do you get?
  34. 34.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.77?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.517? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?941 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.32?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?546 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.769? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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