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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 911 · 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.?733 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?176 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 55 and take away the sum of its digits. What do you get?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 76 and take away the sum of its digits. What do you get?
  7. 7.?134 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.61? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.56?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 18 and take away the sum of its digits. What do you get?
  12. 12.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 53 and take away the sum of its digits. What do you get?
  14. 14.592? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?183 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 92 and take away the sum of its digits. What do you get?
  19. 19.Take 78 and take away the sum of its digits. What do you get?
  20. 20.670? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 84 and take away the sum of its digits. What do you get?
  22. 22.Take 88 and take away the sum of its digits. What do you get?
  23. 23.Take 40 and take away the sum of its digits. What do you get?
  24. 24.Take 13 and take away the sum of its digits. What do you get?
  25. 25.Take 97 and take away the sum of its digits. What do you get?
  26. 26.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?739 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 51 and take away the sum of its digits. What do you get?
  29. 29.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?301 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?815 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.178? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.66?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?741 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?428 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?523 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.8?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 16 and take away the sum of its digits. What do you get?

Answer key

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

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