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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 604 · 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.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.30?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 96 and take away the sum of its digits. What do you get?
  5. 5.Take 74 and take away the sum of its digits. What do you get?
  6. 6.Take 40 and take away the sum of its digits. What do you get?
  7. 7.?156 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.506? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 75 and take away the sum of its digits. What do you get?
  10. 10.Take 57 and take away the sum of its digits. What do you get?
  11. 11.Take 29 and take away the sum of its digits. What do you get?
  12. 12.Take 35 and take away the sum of its digits. What do you get?
  13. 13.?373 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 98 and take away the sum of its digits. What do you get?
  20. 20.83?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.295? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 85 and take away the sum of its digits. What do you get?
  23. 23.?287 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 67 and take away the sum of its digits. What do you get?
  25. 25.Take 78 and take away the sum of its digits. What do you get?
  26. 26.4?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.724? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 22 and take away the sum of its digits. What do you get?
  29. 29.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 71 and take away the sum of its digits. What do you get?
  32. 32.290? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 15 and take away the sum of its digits. What do you get?
  36. 36.?997 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 12 and take away the sum of its digits. What do you get?
  38. 38.163? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.490? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 60 and take away the sum of its digits. What do you get?

Answer key

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

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