The chemical formula for trimethyl phosphite is (CH₃O)₃P.

Here's how it's broken down:

* (CH₃O)₃: This represents three methoxy groups (CH₃O). Each methoxy group consists of a methyl group (CH₃) attached to an oxygen atom (O).

* P: This represents a phosphorus atom.

So, the entire formula indicates that three methoxy groups are bonded to a central phosphorus atom.