Excel can be used for all sorts of things, but one thing it is very good at is calculations. This month we share some fundamental formulas so you never have to reach for your calculator again!

The advantage of formulas is that they are live and automatically update if the information used in the calculation changes. Unlike calculators, once the formula is in place, it will always tell you what the result is.

Starting with the basics – all formulas start with an equals sign. If you ever want to check a formula, or change it later on, you can do so by selecting the cell that contains the formula, and then pressing the F2 key, or you can view it in the formula bar, just above Row 1.

=sum() will add up the numbers in one or more cells. To easily enter it, type “=sum(“ and then use your mouse to select the cells you want to add up. If the cells are not contiguous, press and hold the “CTRL” key. Finally, enter the closing bracket “)” and then press Enter.

=average() will calculate the average of the numbers in a group of cells. Type “=average(“ and then select on the cells you want to include in this calculation, and then close the bracket and press enter. The Average formula ignore any blank cells in the range you specify, but does include 0 values in its calculation.

=today() is not really for calculations, but it will insert todays date into a cell, and automatically update so it’s always the current date. Unlike the other formulas, nothing is entered between the brackets. This is particularly good for anything you plan to print. If you would rather the date didn’t update automatically, you can select the cell and press the “CTRL” and “;” keys together.

=days() is used to calculate how many days there are between two dates. Enter the dates in two separate cells, and then in a third cell, type “=days(“. Click on the cell that contains the end date, enter a comma, then click the cell that contains the start date. Finally close the brackets, and press enter.

If all you want to do is simple calculations, type in “=” and click on the cell that contains the first number you would like to use, or type a number as part of the formula. Then then use, “+” for adding, “-“ for subtracting and “/” for dividing.

If you are familiar with the term “Order of Operations” you can use brackets to tell the formula how it should calculate the formula. Without brackets, Excel calculates any multiplications before addition and subtraction, for example, this formula =5+2*3 would calculate as 11, whereas the same formula with brackets, =(5+2)*3 would equal 21, which is 7 times 3.