Adding to the Database...

Here is the full answer:

\(\begin{align*} \dbinom{15}{2} &= \dfrac{15!}{13!2!} \\ &= \dfrac{15\times 14}{2\times 1} \\ &= 15 \times \dfrac{14}{2} \\ &= 15 \times 7 \\ &= \boxed{105}. \end{align*}\)

15nCr2 =105

Very nice, Mr. O   !!!!!!