How to open Arithmancy doors in Hogwarts Legacy

One of the first puzzles you will encounter during your journey as a student in Hogwarts Legacy is the Arithmancy Door, a locked room containing treasure chests with clothing and Room of Requirement decorations. Unlike the typical doors with locks that you can find throughout the world, Arithmancy Doors cannot be opened using Alohomora, regardless of your level of the Spell. Instead, this puzzle type involves a simple game of addition by using the numbers and symbols shown on the chalkboard and outer frame of the door. Once you understand the basics of how to solve one, you will be able to easily unlock all eleven Arithmancy Doors in Hogwarts.

Related: All landing platform locations in Hogwarts Legacy

Arithmancy Door Puzzle Solution in Hogwarts Legacy

To open an Arithmancy Door, you must approach the puzzle in Hogwarts Legacy as you would solve an addition problem. Every door will have three addends and a sum. The sum will always appear as a one- or two-digit number on the chalkboard, while the addends can be a numeral or a creature symbol. The numerals naturally refer to the exact numbers they portray, but the numerical value of each symbol stems from the outer frame of the Arithmancy Door.

For instance, if we look at the Arithmancy Door in the Astronomy Wing near the Charms Classroom Floo Flame, we will see the sums of the puzzle are “5” and “12,” respectively. The top addition problem displays “3 + 0 + ? = 5” and the bottom shows “Unicorn + 4 + ?? = 12.” The question marks refer to the two rotating buttons on the wall near the Arithmancy Door. Now that we understand the math problems for this particular, it is time to solve them to open the Arithmancy Door in Hogwarts Legacy. 

For the top addition problem, the first “?” should be the number “2,” which we can input using the button on the left of the Arithmancy Door in Hogwarts Legacy. The button mechanism only displays creature symbols, but these symbols correlate to a numbered order of one to nine based on the frame of the puzzle’s door. Accordingly, the “2” symbol we are looking for is the Graphorn head, based on the door frame. 

Next, you will remember that the second problem had a Unicorn head. Looking at the door frame again, we can deduce that the corresponding number is “1.” Four plus one is five, and twelve minus five is seven, meaning that the creature symbol equal to “7” is the solution for the “??” button, which is the squid-shaped icon. Once you have input the correct symbols into the two buttons, approach the Arithmancy Door to open it in Hogwarts Legacy. 

Every Arithmancy Door in Hogwarts is solved using the same method explained above, with two addition problems and two buttons with symbols corresponding to the puzzle’s door frame. If you ever have trouble finding the buttons, remember to cast Revelio to easily spot their nearby positions.