The correct method is to address them from left to right as the are written in the equation. Lastly, addition and subtraction (AS). When only those two operations remain, the sum can be solved ...

But do you know how to insert a sum without typing the formula? Have you struggled to start a new line of text within a cell? Well, you need to learn these less popular but extremely useful shortcuts.

This gives 8 × 180 = 1440. The interior angles in a decagon sum to 1440°. The second method is to use the formula: sum of interior angles = (𝒏 – 2) × 180. This gives (10 – 2) × 180 ...

To check your work, click the cell with the sum and look at the formula bar atop the screen. It will show the details of the calculation. Insider receives a commission when you buy through our links.