I put something on Facebook that is relevant to this topic:
Quote
In order of familiarity with languages, I have:
Z80 Assembly, English, Mathematics, TI-BASIC, French, C, Python, German, Spanish, Mandarin, Physics.
I am not really sure of the order for English and Z80 Assembly, but English is much more complicated. My reading comprehension is better for C than Python, but writing is worse. I know how to ask for where my pants are located in all but Physics and Mandarin. In mathematics, there is no need to ask as the answer can be deduced from the appropriate axioms.
I thought Mandarin would be difficult to learn since I have difficulty with picturing things, but it has been surprisingly easy and it makes a lot of sense so far. (I started yesterday, so I have learned about 50 characters (.1% of them?)

). Writing is something I am still working on and it is giving me a wonderful mental workout

I did a quiz on Memrise which is currently down and I missed a single question out of over 100.
I am far from fluent in French, but in some areas my French is as developed as my native English. (I am supposed to be writing a five page and three page paper in French, at the moment.)
I have been learning German in both English and French. In other words, I have been learning German by doing online lessons intended for native French speakers. There are some conflicts with translations. Some words that I have learned via French will use "die" "das" or "der" and it will be different as I learn them in English, which is confusing. I have just learned to use my gut instinct for that stuff

I probably know less Spanish than German, but I probably know Spanish grammar better than German grammar.
I have read Russian before, though I never formally learned any Russian (I used my knowledge of the alphabet being brought by the Byzantines to figure out the sounds of the letters and that it should be similar to the romance languages and it worked).
I have not learned Arabic, Hebrew, or Japanese for the same reasons that I didn't try Mandarin-- I thought the symbols would be too complicated for me, but I want to give it a try now!
I imagine Portuguese and Italian shouldn't be too difficult once I get French and Spanish fixed in my brain