# Function leafCount Gives the number of "leaf nodes" in the parse tree of the given expression A leaf node is one that has no subexpressions, essentially either a symbol or a constant. Note that `5!` has just one leaf, the '5'; the unary factorial operator does not add a leaf. On the other hand, function symbols do add leaves, so `sin(x)/cos(x)` has four leaves. The `simplify()` function should generally not increase the `leafCount()` of an expression, although currently there is no guarantee that it never does so. In many cases, `simplify()` reduces the leaf count. ## Syntax ```js leafCount(expr) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `expr` | Node | string | The expression to count the leaves of ### Returns Type | Description ---- | ----------- number | The number of leaves of `expr` ### Throws Type | Description ---- | ----------- ## Examples ```js math.leafCount('x') // 1 math.leafCount(math.parse('a*d-b*c')) // 4 math.leafCount('[a,b;c,d][0,1]') // 6 ``` ## See also [simplify](simplify.md)