To set up the Quantity function, start by logging into the backend and going to the Menu.
Enter the menu items and enter the price per unit.
Use the Forced Modifier drop down box to select *Quantity.
Don't forget to Save.
For example, if your location sells Frozen Yogurt by the ounce, enter the cost per ounce in the price field.
Once you Reload Settings on the frontend, find this menu item on the frontend and tap it. You will be prompted to enter the Quantity.
Lavu will calculate the total for you, based on the price in the backend and the quantity entered on the frontend.