Solution

Past exam of the mathematics course of the University of Cambridge / 2003 / iii / Paper 22 / 1 / Solution

Past exam of the mathematics course of the University of Cambridge / 2003 / iii / Paper 34 / 4 / Solution

Past exam of the mathematics course of the University of Cambridge / 2003 / iii / Paper 69 / 1 / b / Solution

Past exam of the mathematics course of the University of Cambridge / 2005 / ia / Paper 4 / 2E / Solution

Past exam of the mathematics course of the University of Cambridge / 2005 / iii / Paper 12 / 3 / a / Solution

Past exam of the mathematics course of the University of Cambridge / 2005 / iii / Paper 33 / 2 / Solution

Past exam of the mathematics course of the University of Cambridge / 2005 / iii / Paper 3 / 6 / Solution

Past exam of the mathematics course of the University of Cambridge / 2005 / iii / Paper 44 / 5 / b / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / ia / Paper 4 / 2E / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 12 / 1 / i / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 12 / 4 / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 14 / 3 / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 28 / 1 / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 34 / 4 / Solution

Past exam of the mathematics course of the University of Cambridge / 2006 / iii / Paper 45 / 3 / c / Solution

Past exam of the mathematics course of the University of Cambridge / 2007 / ia / Paper 4 / 2E / Solution

Past exam of the mathematics course of the University of Cambridge / 2007 / ia / Paper 5 / 4 / Solution

Past exam of the mathematics course of the University of Cambridge / 2007 / iii / Paper 12 / 2 / Solution

Past exam of the mathematics course of the University of Cambridge / 2007 / iii / Paper 12 / 3 / Solution

{title2=$\binom{n}{k}$}
{wiki}

The <binomial coefficient>
$$
\binom nk=\frac{n!}{k!(n-k)!}
$$
counts the $k$-element subsets of an $n$-element set. Equivalently, it counts strings containing $k$ copies of one symbol and $n-k$ copies of another.

Binomial coefficient

Codex @codex  0

 Incoming links: Binomial coefficient