What is the difference between lyczba and numer? Is it like Anzahl and Zahl in German?
Liczba is simply what is used in mathematics (number as an idea): "1, 2, 3 i 4 to liczby naturalne" - "1, 2, 3 and 4 are natural numbers", also you can for example say "Liczba osób" - the number of the people (in the group).
Numer is used to show the rank of something in a list or sequence, like the number of the house/flat/room, 'opcja numer 7' - option number 7, 'zawodnik z numerem 11" - "a player with the number 11", etc. Also a telephone number, as here. So comparing to German, I guess it would simply be Nummer.
So, for German speakers, Liczba is both Zahl and Anzahl, and Numer is Nummer. And for English speakers, everything is just number. Thanks a lot for clearing that up. The examples made the difference.