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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 380 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.?487 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 12 and take away the sum of its digits. What do you get?
  5. 5.44? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.5?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 25 and take away the sum of its digits. What do you get?
  8. 8.?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.8?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?500 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.7?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 77 and take away the sum of its digits. What do you get?
  13. 13.Take 23 and take away the sum of its digits. What do you get?
  14. 14.?587 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.8?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.891? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 64 and take away the sum of its digits. What do you get?
  18. 18.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 36 and take away the sum of its digits. What do you get?
  20. 20.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 79 and take away the sum of its digits. What do you get?
  22. 22.6?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?156 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.842? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?958 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?686 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.68?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 93 and take away the sum of its digits. What do you get?
  30. 30.Take 69 and take away the sum of its digits. What do you get?
  31. 31.8?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?610 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 56 and take away the sum of its digits. What do you get?
  34. 34.?311 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?694 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.115? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?953 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?375 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.664? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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