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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 530 · 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 30 and take away the sum of its digits. What do you get?
  2. 2.42?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 28 and take away the sum of its digits. What do you get?
  5. 5.4?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.435? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 99 and take away the sum of its digits. What do you get?
  9. 9.?745 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?652 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 26 and take away the sum of its digits. What do you get?
  13. 13.Take 64 and take away the sum of its digits. What do you get?
  14. 14.654? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 36 and take away the sum of its digits. What do you get?
  16. 16.Take 94 and take away the sum of its digits. What do you get?
  17. 17.?969 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.56?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.6?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.77?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 11 and take away the sum of its digits. What do you get?
  22. 22.Take 95 and take away the sum of its digits. What do you get?
  23. 23.?813 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.1?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 17 and take away the sum of its digits. What do you get?
  26. 26.242? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.69?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.33?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.289? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?638 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 97 and take away the sum of its digits. What do you get?
  33. 33.?943 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.215? 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. 36.11?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.586? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 18 and take away the sum of its digits. What do you get?
  39. 39.4?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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