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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 95 · 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. 1.512? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.5?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.50?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.11?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.19?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.3?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.58?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.796? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?577 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.860? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 31 and take away the sum of its digits. What do you get?
  13. 13.2?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 51 and take away the sum of its digits. What do you get?
  15. 15.?102 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.7?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.742? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 41 and take away the sum of its digits. What do you get?
  20. 20.645? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 43 and take away the sum of its digits. What do you get?
  22. 22.8?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 21 and take away the sum of its digits. What do you get?
  24. 24.?553 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.22?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?545 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 97 and take away the sum of its digits. What do you get?
  28. 28.Take 62 and take away the sum of its digits. What do you get?
  29. 29.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 26 and take away the sum of its digits. What do you get?
  31. 31.39?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 11 and take away the sum of its digits. What do you get?
  33. 33.Take 57 and take away the sum of its digits. What do you get?
  34. 34.Take 67 and take away the sum of its digits. What do you get?
  35. 35.Take 42 and take away the sum of its digits. What do you get?
  36. 36.?021 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 79 and take away the sum of its digits. What do you get?
  38. 38.Take 56 and take away the sum of its digits. What do you get?
  39. 39.Take 16 and take away the sum of its digits. What do you get?
  40. 40.Take 20 and take away the sum of its digits. What do you get?

Answer key

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

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