Binomial coefficient / choose (n choose k) in LaTeX

Binomial coefficient / choose (n choose k)

Operators

(ⁿₖ)

LaTeX command

\binom{n}{k}

Use inside math mode: $\binom{n}{k}$ — needs \usepackage{amsmath}

\binom is the amsmath command and is what KaTeX supports. The older \choose is a plain-TeX primitive that still works in LaTeX but is discouraged because it needs the enclosing braces to behave.

All ways to write it

Command	Use	Package
`\binom{n}{k}`	—	amsmath
`{n \choose k}`	old TeX form, still works	none
`\dbinom{n}{k}`	display size	amsmath
`\tbinom{n}{k}`	text size	amsmath
`C(n, k)`	function notation	none
`{}^{n}C_{k}`	prescript notation	none

Commands marked with a package need that \usepackage line in a LaTeX document.

Example

(x + y)^n = \sum_{k=0}^{n} \binom{n}{k} x^{n-k} y^{k}

The binomial theorem.

Questions

Does \choose work in KaTeX?

Yes, both \binom and {n \choose k} render in KaTeX and MathJax.

Related symbols

Fractions ½ \frac{a}{b}
Summation ∑ \sum_{i=1}^{n}
Product ∏ \prod_{i=1}^{n}

Using choose in Confluence

Confluence Cloud has no built-in LaTeX. With LaTeX Math for Confluence you add a math macro to any page, type \binom{n}{k} and it renders inline or as a block, with a live preview while you edit. Every command on this page renders there without extra packages.