You can control Office Math without a mouse.
If you want to insert a formula into a text document, and you already know the correct writing, you can proceed as follows:
Write the formula into your text
Select the formula
Choose the command Insert - OLE Object - Formula Object.
Move left or right to the next category or function.
Selects a category (within the category section) or inserts a function in the Commands window (within the function section).
Jump from the first category item to the first function of the category.
Jump from the last category item to the last function of the category.