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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 677 · 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 97 and take away the sum of its digits. What do you get?
  2. 2.57?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 74 and take away the sum of its digits. What do you get?
  4. 4.834? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 41 and take away the sum of its digits. What do you get?
  7. 7.4?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 36 and take away the sum of its digits. What do you get?
  9. 9.489? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?940 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.214? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 33 and take away the sum of its digits. What do you get?
  15. 15.84?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.626? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 60 and take away the sum of its digits. What do you get?
  18. 18.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 76 and take away the sum of its digits. What do you get?
  20. 20.7?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?188 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 38 and take away the sum of its digits. What do you get?
  24. 24.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.3?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 92 and take away the sum of its digits. What do you get?
  29. 29.3?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.36?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.29?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 54 and take away the sum of its digits. What do you get?
  34. 34.78?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 46 and take away the sum of its digits. What do you get?
  36. 36.417? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.88? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 28 and take away the sum of its digits. What do you get?

Answer key

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

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