Write a formulaBudgetingYou can write a formula using the dropdown rather than typing it, and read the error when one does not resolve.Formula fields open a small editor with an autocomplete list rather than a plain text box. It opens **over** the cell so the list is not clipped.1. Let the dropdown write itClick into the field. With the field empty — or straight after an operator — the list opens as a **menu**:A **Recent** section joins them once you have inserted something before.Navigate with **↑ ↓**, open a submenu with **→**, close it with **←**, insert with **Enter**.Start typing instead and the list switches to a **filter**: a flat, prefix-matched list under Recent, Functions and Variables.Typing names by hand works, but the dropdown is worth the habit — it inserts exactly the spelling the engine expects, and a misspelled reference is an error rather than a wrong number.2. Combine with operators`+ - * /` and parentheses. The dropdown reopens after an operator, so a whole expression can be assembled without typing a name.3. Insert a function's argument from a listFunctions that take an argument offer their own submenu — pick the account, and the whole call is written for you:The same menu is how you [reference another account](/kb/article/reference-another-account-in-a-formula).4. Read the errorsThree are caught as you type: an **empty** expression, **unbalanced parentheses**, and **invalid characters**.A different kind survives saving: a formula that parses but points at something that no longer exists — a renamed company, a deleted account. That shows as a **red frame** on the cell. The formula is not broken arithmetic; it is a reference with nothing at the other end, and it needs the reference fixed rather than the maths.5. Check what you wroteCells show results, not formulas. Use the **fx** toggle to read them back — see [switch between values and formulas](/kb/article/switch-between-values-and-formulas).Markdown