By Conrad Carlberg

If you’re about to array-enter a formula that will occupy a range of cells on the worksheet, you need to know the dimensions of that range. That’s because array formulas and the functions that they employ do not automatically populate the necessary range of cells. You need to begin by selecting that range yourself.

Knowing the range’s dimensions is largely a matter of experience. If you’re about to array-enter the LINEST function, for example, you need to know that you should start by selecting a range that’s five rows high and with as many columns as you have predictor variables, plus 1.

So if you have one variable to be predicted in, say, column A and two predictor variables in columns B and C, you’re expected to know that you need to start by selecting a range that’s at least five rows high and at least three columns wide, such as E1:G5.