How to Quickly Find the Sum of a Spreadsheet Column

Right now some of my students are designing their own Arduino projects. I have money for them to spend on materials, but they have to stay within the budget allotted to them. I’m having them use Google Sheets to keep track of materials and budget. Last week I noticed one student tallying her materials cost by hand. I used that as a chance to show the class how to use the built-in sum function in Google Sheets to tally the value of a column.