To start, the chart on the left will help you know how many servings the cake you ordered will serve. Make sure to note the numbers on the right side will be serving size normal for any event other than a wedding. The left side is what is left up to the professional cake cutters for weddings. The also same goes for square cakes!
In case you are doing the dirty work of cutting the cake, the chart on the right is a guide of getting the most out of your cake! Or, it could double as a way to get yourself half the cake and still feed the rest of your guests. No worries- your secret is safe with me! Yay for circles and triangles!