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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 983 · 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 95 and take away the sum of its digits. What do you get?
  2. 2.Take 38 and take away the sum of its digits. What do you get?
  3. 3.81? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.85? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 88 and take away the sum of its digits. What do you get?
  6. 6.11?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 89 and take away the sum of its digits. What do you get?
  8. 8.332? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.112? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.81?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.89?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 72 and take away the sum of its digits. What do you get?
  13. 13.?129 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.840? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 43 and take away the sum of its digits. What do you get?
  17. 17.493? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?669 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 28 and take away the sum of its digits. What do you get?
  23. 23.Take 74 and take away the sum of its digits. What do you get?
  24. 24.1?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 90 and take away the sum of its digits. What do you get?
  26. 26.728? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?713 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.16?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 64 and take away the sum of its digits. What do you get?
  30. 30.7?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.35?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 66 and take away the sum of its digits. What do you get?
  34. 34.Take 42 and take away the sum of its digits. What do you get?
  35. 35.71? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.6?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.438? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 39 and take away the sum of its digits. What do you get?

Answer key

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

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