In this post, I’ll teach you how to solve the “Math doors” that are around the castle. The first thing you’re going to want to find is the “cheat sheet” that can be found outside of the Arithmancy Classroom, which is down the hall in the rafter section from the Divination Fast Travel spot. There you will find this in a box on the bench to the right of the chalkboard.
The beasts number 0-9, not 1-8, so keep that in mind. Below I’ll show the math for each door as well as provide a link to the video for each one.
Arithmancy Classroom Door & the 2 inside
This is the one by the Divination Classroom fast travel spot in the rafters. Get the “cheat sheet” here. There is the original door to get into the classroom (9 & 4) and then there are two doors inside the classroom that you can also open.
Classroom door
9 = 2 + snake (3) = ? (4, which is the owl)
4 = 0 + 1 + ?? (3, which is the snake)
Owl and snake
Inside the classroom
15 = crab (5) + lizard (6) + ? (4, which is owl)
18 = 13 + beast (0) + ?? (5, which is crab)
Owl and crab
Inside the classroom
17 = 6 + crab (5) + ? (6, which is lizard)
8 = 0 + octopus (7) + ?? (1, which is unicorn)
Lizard and unicorn
Central Hall 21 & 17
This door is in the Central Hall, just to the right of the door to the Transfiguration Courtyard. The second spinny is up a level.
21 = 11 + two-horned animal (2) + ? (8, which is spider)
17 = crab (5) + mandrake (9) + ?? (3, which is 3-headed snake)
Spider & snake
Grand Staircase 6 & 11
From the Faculty Tower fast travel spot, head towards the Grand Staircase tower column and go right when you reach it. The second twirly thing is by the Grand Staircase fast travel spot.
6 = 4 + two-horned (2) + ? (0, which is the demiguise)
11 = 5 + 1 + ?? (5, which is the crab)
Upstairs twirly – crab
Downstairs twirly – demiguise
Grand Staircase Tower Location 23 & 19
This is to the left of the fast travel spot down the hall. At the base of the stairs to the Ravenclaw Common Room.
23 = 15 + two-horned (2) + ? (6, which is lizard)
19 = three-headed snake (3) + mandrake (9) + ?? (7, which is octopus)
Lizard and octopus
Ravenclaw Tower 13 & 21
This is just down from the Ravenclaw Tower fast travel spot.
13 = 1 + spider (8) + ? (4, which is the owl)
21 = 13 + snake (3) + ?? (5, which is the crab)
Owl and crab
Bell Tower Locked Door 22 & 9
When you get the Alohomora I in The Caretaker’s Lunar Lament, you’ll be able to unlock the level 1 hallway under the potions classroom or from the Bell Tower Courtyard.
22 = 12 + spider (8) + ? (2, which is the two-horned thing).
9 = octopus (7) + unicorn (1) + ?? (1, which is unicorn)
Two-horned and unicorn
Charms Class Location 5 & 12
From the statue outside of the Charms classroom, go up the stairs and around to the left.
5 = 3 + 0 + ? (2 which is the two-horned thing)
12 = 4 + unicorn (1) + ?? (7, which is the octopus)
Two-horned thing & octopus
Faculty Tower 13 & 14
When you get the Alohomora I in The Caretaker’s Lunar Lament, you’ll finally be allowed in the locked Faculty Tower. This is up one level from the main hallway door.
13 = 5 + spider (8) + ? (0, which is demguise)
14 = 3 + 2-horned (2) + ?? (9, which is the mandrake)
Demiguise & madrake
Locked Music Hallway 10 & 7
When you get the Alohomora I in The Caretaker’s Lunar Lament, you can head up to the Music Room floor. Go through the level 1 locked door down the hall from the Music Rom.
10 = 2 + 2-headed (2) + ? (6, which is lizard)
7 = 3 + 1 + ??, (2, which is the two-headed snake)
Lizard and snake
Great Hall 24 & 14
When you enter the Great Hall and look towards the tables and chairs, this is around to your left.
24 = 7 + mandrake (9) + ? (8, which is the spider)
14 = 11 + demiguise (0) + ?? (3, which is the three-headed snake)
Spider & snake