The SUM function sums numeric values. For example, if I enter the formula =SUM(B7:B11) Excel will return "50," the total of all numbers in that range.
SUM simply ignores blank cells.
The formula =SUM(D7:E9) will return "1,350". Like blanks, SUM ignores text values.
In addition to ranges, SUM can work with individual cells, too. Just separate each additional item with a comma. As you enter these values in, you're free to combine both ranges and individual cell references.
Like other functions that accept multiple values, you can hold down the Control key (Command on a Mac) and Excel will add the commas for you each time you click a new location on the worksheet.
Here, I can use that technique to SUM all of the ranges and cells we've worked with so far.
You can select each of these values individually using the formula hint window that appears when you're editing a function. This is a good way to fix a mistake.
The Excel SUM function returns the sum of values supplied. These values can be numbers, cell references, ranges, arrays, and constants, in any combination. SUM can handle up to 255 individual arguments.