How to find 'r' in the NCR equation with n and answer known The value of $n = 105$. $\binom nr = 187460$. How do i find the value of r?

$\binom{n}{k}$ is close to $\frac{n^k}{k!}$ when $n$ is considerably larger than $k$.
So it goes like $100,100^2/2,100^3/6\dots100^4/24$
The number you want is close to the third one and far from the other.
Also note that $\binom{n}{k}$ increases as $k$ gets close to $n/2$
