#### Answer

4851

#### Work Step by Step

A positive integer less than 100 can be any of: $1, 2, 3, ... , 99$
Therefore, a set of two positive integers less than 100 can be chosen in C(99, 2) ways. [By the definition of C(n, r) ]
C(99, 2) = $\frac{99!}{(99-2)!\times 2!}$
= $\frac{99\times98\times97!}{97!\times 2!}$
=$\frac{99\times98}{2!}$
=$\frac{99\times98}{2}$
=