Africa dwarfs Algeria: about 30,370,000 km² km² against 2,322,788 km² km². At true size Africa is about 13.1× larger — the whole of Algeria fits into Africa roughly 13 times.
The old Mercator map treated both about equally (1× vs 1.3× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Algeria fits 13× into Africa.