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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 383 · 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 73 and take away the sum of its digits. What do you get?
  2. 2.Take 87 and take away the sum of its digits. What do you get?
  3. 3.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 50 and take away the sum of its digits. What do you get?
  5. 5.?699 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?748 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?845 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?267 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 42 and take away the sum of its digits. What do you get?
  10. 10.?240 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 13 and take away the sum of its digits. What do you get?
  12. 12.68? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.13?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.24?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 27 and take away the sum of its digits. What do you get?
  18. 18.Take 18 and take away the sum of its digits. What do you get?
  19. 19.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.4?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.126? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.67?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.166? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 46 and take away the sum of its digits. What do you get?
  25. 25.270? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 74 and take away the sum of its digits. What do you get?
  28. 28.Take 78 and take away the sum of its digits. What do you get?
  29. 29.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.804? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.8?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 72 and take away the sum of its digits. What do you get?
  35. 35.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.827? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?815 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. 72
  3. 2
  4. 45
  5. 3
  6. 8
  7. 1
  8. 3
  9. 36
  10. 3
  11. 9
  12. 4
  13. 2
  14. 3
  15. 4
  16. 9
  17. 18
  18. 9
  19. 6
  20. 6
  21. 9
  22. 1
  23. 5
  24. 36
  25. 9
  26. 5
  27. 63
  28. 63
  29. 1
  30. 6
  31. 7
  32. 36
  33. 1
  34. 63
  35. 6
  36. 6
  37. 8
  38. 1
  39. 3
  40. 4

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