Answer
$105$
Work Step by Step
Formula to calculate the Binomial Coefficient is:
$\displaystyle \binom{n}{k}=\dfrac{n!}{k!(n-k)!}$
Let's see how this formula works:
$\displaystyle \binom{15}{2}=\dfrac{15!}{2!(15-2)!}=\dfrac{ 15 \cdot 14 \cdot 13!}{2 \cdot 1 \cdot 13!}=105$