Nikola Z. 
As you explore the castle, you will find some mysterious doors with puzzles on them which are combinations of numbers and animal symbols. If you have a hard time unlocking the Puzzle Door 21 17, then we have a solution for you.
In this guide, we will show you Puzzle Door 21 17 solution in Hogwarts Legacy!
Puzzle Door 21 17 Guide (The Library Annex Central Hall)
Like all other puzzle doors inside the castle, you will see some symbols all around the door’s arch. All you need to do is to match the right symbols and numbers and get the exact number in the middle of the number puzzle.
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The symbols on the doors have corresponding numbers starting from 0 to 9, from the bottom left going to the bottom right of the door.
Each of them has a missing number that you have to obtain by rolling the two question marks that can be found on the walls in the same area of the door.
To solve the puzzle with the number 21, you have to roll the question mark to the symbol that corresponds to the number 8 in order to get a total of 21 when combined with all three numbers from the puzzle.
The second quest mark can be found on the upper platform going through the stairs, and it will be on the front wall. To make it right, roll it to the hydra symbol.
This will combine the three numbers, and get the number 17 in total which will solve the puzzle on the door.
Now, you can open the door and continue forward with the exploration.
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