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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 485 · 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 36 and take away the sum of its digits. What do you get?
  2. 2.18?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.65?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.4?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 47 and take away the sum of its digits. What do you get?
  8. 8.820? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.8?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.351? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.16? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.185? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 39 and take away the sum of its digits. What do you get?
  16. 16.4?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 23 and take away the sum of its digits. What do you get?
  18. 18.39?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 84 and take away the sum of its digits. What do you get?
  20. 20.54?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 87 and take away the sum of its digits. What do you get?
  22. 22.?554 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 14 and take away the sum of its digits. What do you get?
  24. 24.Take 31 and take away the sum of its digits. What do you get?
  25. 25.Take 33 and take away the sum of its digits. What do you get?
  26. 26.Take 90 and take away the sum of its digits. What do you get?
  27. 27.Take 62 and take away the sum of its digits. What do you get?
  28. 28.Take 21 and take away the sum of its digits. What do you get?
  29. 29.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.478? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?854 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.22?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 94 and take away the sum of its digits. What do you get?
  35. 35.?655 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?407 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 59 and take away the sum of its digits. What do you get?
  38. 38.701? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.122? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.21?6 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. 1
  3. 6
  4. 9
  5. 4
  6. 6
  7. 36
  8. 8
  9. 1
  10. 9
  11. 6
  12. 2
  13. 4
  14. 3
  15. 27
  16. 3
  17. 18
  18. 7
  19. 72
  20. 9
  21. 72
  22. 4
  23. 9
  24. 27
  25. 27
  26. 81
  27. 54
  28. 18
  29. 7
  30. 5
  31. 8
  32. 1
  33. 1
  34. 81
  35. 2
  36. 7
  37. 45
  38. 1
  39. 4
  40. 9

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