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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 549 · 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 76 and take away the sum of its digits. What do you get?
  2. 2.5?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 37 and take away the sum of its digits. What do you get?
  4. 4.?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.34?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 66 and take away the sum of its digits. What do you get?
  8. 8.Take 19 and take away the sum of its digits. What do you get?
  9. 9.6?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 86 and take away the sum of its digits. What do you get?
  11. 11.?382 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.503? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 11 and take away the sum of its digits. What do you get?
  14. 14.Take 27 and take away the sum of its digits. What do you get?
  15. 15.Take 79 and take away the sum of its digits. What do you get?
  16. 16.Take 78 and take away the sum of its digits. What do you get?
  17. 17.Take 80 and take away the sum of its digits. What do you get?
  18. 18.39?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.6?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 30 and take away the sum of its digits. What do you get?
  21. 21.803? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 18 and take away the sum of its digits. What do you get?
  23. 23.Take 47 and take away the sum of its digits. What do you get?
  24. 24.631? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.3?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.692? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 20 and take away the sum of its digits. What do you get?
  28. 28.?905 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 54 and take away the sum of its digits. What do you get?
  30. 30.?466 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.21?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.8?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 77 and take away the sum of its digits. What do you get?
  37. 37.64?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.225? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.36?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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