Array formulas are powerful formulas that enable you to perform complex calculations that often can’t be done with standard worksheet functions. They are also referred to as "Ctrl-Shift-Enter" or "CSE" formulas, because you need to press Ctrl+Shift+Enter to enter them. You can use array formulas to do the seemingly impossible, such as
Count the number of characters in a range of cells.
Sum numbers that meet certain conditions, such as the lowest values in a range or numbers that fall between an upper and lower boundary.
Sum every nth value in a range of values.
Excel provides two types of array formulas: Array formulas that perform several calculations to generate a single result and array formulas that calculate multiple results. Some worksheet functions return arrays of values, or require an array of values as an argument.