Africa dwarfs Nigeria: about 30,370,000 km² km² against 911,496 km² km². At true size Africa is about 33.3× larger — the whole of Nigeria fits into Africa roughly 33 times.
The old Mercator map treated both about equally (1× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Nigeria fits 33× into Africa.