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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 788 · 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. 1.1?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.373? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.729? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.549? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.28?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 21 and take away the sum of its digits. What do you get?
  9. 9.67?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.376? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.226? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.2?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 12 and take away the sum of its digits. What do you get?
  15. 15.21?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 83 and take away the sum of its digits. What do you get?
  17. 17.Take 98 and take away the sum of its digits. What do you get?
  18. 18.84?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.84?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.144? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.79?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.8?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.20?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 70 and take away the sum of its digits. What do you get?
  25. 25.Take 15 and take away the sum of its digits. What do you get?
  26. 26.Take 94 and take away the sum of its digits. What do you get?
  27. 27.Take 26 and take away the sum of its digits. What do you get?
  28. 28.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?752 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 20 and take away the sum of its digits. What do you get?
  31. 31.Take 79 and take away the sum of its digits. What do you get?
  32. 32.Take 72 and take away the sum of its digits. What do you get?
  33. 33.23?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 22 and take away the sum of its digits. What do you get?
  35. 35.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 30 and take away the sum of its digits. What do you get?
  38. 38.810? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 39 and take away the sum of its digits. What do you get?
  40. 40.65?7 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. 9
  3. 5
  4. 9
  5. 9
  6. 6
  7. 1
  8. 18
  9. 4
  10. 1
  11. 2
  12. 8
  13. 6
  14. 9
  15. 2
  16. 72
  17. 81
  18. 4
  19. 6
  20. 9
  21. 1
  22. 6
  23. 4
  24. 63
  25. 9
  26. 81
  27. 18
  28. 1
  29. 4
  30. 18
  31. 63
  32. 63
  33. 1
  34. 18
  35. 4
  36. 1
  37. 27
  38. 9
  39. 27
  40. 9

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