Entering Matrix Formulas
The following is an example of how you can enter a matrix formula, without going into the details of matrix functions.
Assume you have entered 10 numbers in Columns A and B (A1:A10 and B1:B10), and would like to calculate the sum of each row in Column C.

Using the mouse, select the range C1:C10, in which the results are to be displayed.

Press F2, or click in the input line of the Formula bar.

Enter an equal sign (=).

Select the range A1:A10, which contains the first values for the sum formula.

Press the (+) key from the numerical keypad.

Select the numbers in the second column in cells B1:B10.

End the input with the matrix key combination: Shift+Command Ctrl+Enter.
The matrix area is automatically protected against modifications, such as deleting rows or columns. It is, however, possible to edit any formatting, such as the cell background.