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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 555 · 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. 1.4?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.554? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?101 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 34 and take away the sum of its digits. What do you get?
  7. 7.Take 89 and take away the sum of its digits. What do you get?
  8. 8.Take 65 and take away the sum of its digits. What do you get?
  9. 9.Take 25 and take away the sum of its digits. What do you get?
  10. 10.?994 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?417 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.3?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.1?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.1?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.429? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.41?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.747? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 57 and take away the sum of its digits. What do you get?
  21. 21.484? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 45 and take away the sum of its digits. What do you get?
  23. 23.Take 55 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.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 21 and take away the sum of its digits. What do you get?
  27. 27.?406 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?840 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.24? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 11 and take away the sum of its digits. What do you get?
  33. 33.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 72 and take away the sum of its digits. What do you get?
  35. 35.Take 43 and take away the sum of its digits. What do you get?
  36. 36.29?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?602 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?185 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?723 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.83?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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