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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 515 · 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.Take 95 and take away the sum of its digits. What do you get?
  2. 2.5?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.338? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 53 and take away the sum of its digits. What do you get?
  5. 5.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 70 and take away the sum of its digits. What do you get?
  7. 7.659? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 16 and take away the sum of its digits. What do you get?
  9. 9.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 83 and take away the sum of its digits. What do you get?
  11. 11.67?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?253 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.834? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.73?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.808? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.496? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?892 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.193? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 77 and take away the sum of its digits. What do you get?
  24. 24.?466 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.354? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.51?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.6?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?533 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.31?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?278 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.263? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.77?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 44 and take away the sum of its digits. What do you get?
  38. 38.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.8?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.4?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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