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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 756 · 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. 1.6?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 28 and take away the sum of its digits. What do you get?
  4. 4.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.43?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 91 and take away the sum of its digits. What do you get?
  7. 7.Take 77 and take away the sum of its digits. What do you get?
  8. 8.614? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 35 and take away the sum of its digits. What do you get?
  10. 10.39?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 63 and take away the sum of its digits. What do you get?
  12. 12.539? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.421? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.42?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.19?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 75 and take away the sum of its digits. What do you get?
  17. 17.Take 15 and take away the sum of its digits. What do you get?
  18. 18.Take 95 and take away the sum of its digits. What do you get?
  19. 19.Take 52 and take away the sum of its digits. What do you get?
  20. 20.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 22 and take away the sum of its digits. What do you get?
  22. 22.Take 89 and take away the sum of its digits. What do you get?
  23. 23.1?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.1?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 11 and take away the sum of its digits. What do you get?
  26. 26.841? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 46 and take away the sum of its digits. What do you get?
  28. 28.?616 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.51?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 39 and take away the sum of its digits. What do you get?
  31. 31.Take 94 and take away the sum of its digits. What do you get?
  32. 32.1?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.17?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.474? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.2?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.49?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 9
  2. 2
  3. 18
  4. 2
  5. 9
  6. 81
  7. 63
  8. 7
  9. 27
  10. 8
  11. 54
  12. 1
  13. 2
  14. 8
  15. 3
  16. 63
  17. 9
  18. 81
  19. 45
  20. 1
  21. 18
  22. 72
  23. 6
  24. 2
  25. 9
  26. 5
  27. 36
  28. 5
  29. 2
  30. 27
  31. 81
  32. 9
  33. 1
  34. 6
  35. 3
  36. 1
  37. 1
  38. 1
  39. 2
  40. 5

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