Saying "Paul Erdos' combinatorial problem" is like saying "Michael Jordan's dunk he made that one time."

+1 insightful

According to a rigorous scientific study I just conducted, 7.

The land mass of the earth is about 147 million square miles. A population of 600,000 leaves about a person every 250 square miles. Assuming that the devastation which wiped out 99.99% of the population also has some deleterious effect on our ability to rapidly traverse 50 miles and accurately find other living beings, attaining sufficient reproducing to keep the population over a minimal threshold level would be rather difficult.

Numbers alone do not keep a species alive.