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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 810 · 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 58 and take away the sum of its digits. What do you get?
  2. 2.3?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.3?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 92 and take away the sum of its digits. What do you get?
  6. 6.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.5?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 30 and take away the sum of its digits. What do you get?
  9. 9.?097 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.26?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 80 and take away the sum of its digits. What do you get?
  14. 14.4?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 77 and take away the sum of its digits. What do you get?
  16. 16.8?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.169? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?485 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 99 and take away the sum of its digits. What do you get?
  20. 20.79?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 33 and take away the sum of its digits. What do you get?
  24. 24.6?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.688? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.275? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 24 and take away the sum of its digits. What do you get?
  29. 29.4?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 57 and take away the sum of its digits. What do you get?
  33. 33.Take 49 and take away the sum of its digits. What do you get?
  34. 34.Take 65 and take away the sum of its digits. What do you get?
  35. 35.8?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 29 and take away the sum of its digits. What do you get?
  37. 37.37?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 62 and take away the sum of its digits. What do you get?
  39. 39.?223 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.1?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 45
  2. 1
  3. 7
  4. 9
  5. 81
  6. 7
  7. 3
  8. 27
  9. 2
  10. 7
  11. 2
  12. 3
  13. 72
  14. 3
  15. 63
  16. 8
  17. 2
  18. 1
  19. 81
  20. 2
  21. 8
  22. 1
  23. 27
  24. 5
  25. 5
  26. 3
  27. 4
  28. 18
  29. 8
  30. 7
  31. 7
  32. 45
  33. 36
  34. 54
  35. 1
  36. 18
  37. 8
  38. 54
  39. 2
  40. 5

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