Here are some basic formula modules.
The fist instance is a simple ( a+b=c ) formula.
Tthe second is a freelancer cost estimator ( rate x hours + tax ) with a fixed/unchangeable rate field.
The third is a square root formula that rounds up/down to the closest whole number.
Note the way the examples below are styled are using the standard template module class suffix. No custom CSS has been added. You can use your own templates style or create your own CSS. As always, if you need assistance with styling, just open a support ticket.