South America dwarfs Zambia: about 17,840,000 km² km² against 755,593 km² km². At true size South America is about 23.6× larger — the whole of Zambia fits into South America roughly 23 times.
The old Mercator map treated both about equally (1× vs 1.1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Zambia fits 23× into South America.