Click the cell where you want the total to appear
Type `=SUM(A1:Z1)` replacing `A1:Z1` with your row range
Press Enter
To add all numbers in the entire row, use `=SUM(1:1)`
To add a different row, change the row number in the formula, such as `=SUM(2:2)`
To add only selected cells in a row, use `=SUM(A1,C1,E1)`
To copy the formula to other rows, drag the fill handle down
To use the toolbar, click the cell, then click the Functions icon and choose SUM
To automatically total a row with changing columns, use the SUM formula across the needed range