How to use a formula field?

Calculoid formula field applies similar logic as Google Spreadsheet and MS Excel, you create the formula by adding fields identifiers into the calculation. In Calculoid you can select fields by their name and add them to the formula with just a click. Please remember you do not need to start the formula using = and also you do not need brackets for multiplying operations, only use brackets where totally necessary. 

Find out more about syntax and operators in this blog post.