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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 638 · 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.?820 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.782? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 40 and take away the sum of its digits. What do you get?
  4. 4.Take 35 and take away the sum of its digits. What do you get?
  5. 5.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 48 and take away the sum of its digits. What do you get?
  8. 8.?581 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.32?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?038 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.592? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 22 and take away the sum of its digits. What do you get?
  14. 14.?289 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.3?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.4?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.491? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?248 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.85?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.45?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 89 and take away the sum of its digits. What do you get?
  25. 25.3?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 53 and take away the sum of its digits. What do you get?
  27. 27.334? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.109? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 98 and take away the sum of its digits. What do you get?
  30. 30.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.41?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?577 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.40?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 20 and take away the sum of its digits. What do you get?
  35. 35.?696 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 56 and take away the sum of its digits. What do you get?
  37. 37.8?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.888? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 66 and take away the sum of its digits. What do you get?
  40. 40.Take 17 and take away the sum of its digits. What do you get?

Answer key

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

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