Well there are multiple solutions here. There isn't such thing as a 3d matrix on the calculator, but you have a few options, some more advanced than others.
1) A matrix can be no larger than 20x20. I'm imagining you probably want a matrix of 16x8, but if you had smaller rooms you could probably fit 4 small rooms in the same matrix. This is probably not a very useful option.
2) You can use multiple matrices, but there are only 10 which are [A] [B] [C] [D] [E] [F] [G] [H] [I] and [J].
3) If you want to store multiple rooms in the same matrix, you can put fractional parts at different decimal placements for separate rooms. But that can be difficult for a newcomer and I don't have the time to go into that at the moment.
4) You can use lists (even your own custom lists if you want, but that can be slower), and assuming your rooms are 16x8 then your lists would equate to 128 elements long. This would require some reworking with your math, as checking neighbors would require you to go up or down the list different amounts whether you are checking the neighbor up left right or down. But with a list you could have speed improvements, memory saving improvements, and you can separate the list into rows by going every 16.
You could also use fractional parts for different rooms with lists if you want.
5) You could use one entire list for up to 7 different rooms. 16x8=128, so 128*7=896 and you couldn't have an eighth room in the same list because that would surpass 999 elements, the maximum amount of elements you can have in a list. Your list would have each different room 128 elements apart, and each row 16 elements apart. You could use this, but it could also maybe be a bit difficult for a new programmer.
I'd say the best option right now for you is to use the 10 different matrices the calculator has, but if you think you want to tackle any of the other options just let me know.
