Enter functions directly into the worksheet cell for MS DOS Select the cell into which the formula will be entered.

• Insert an equal (=) Sign to begin the formula.  The formula toolbar will appear. 
• Enter the name of the function [e.g.SUM], followed by an opening parenthesis [(] , any arguments required for the function [e.g. E2:E5], and closing parenthesis [)]
• Press Enter. Big there are no errors in the formula,  the result of the function will be entered in the cell.  If you activate the cell again,  the function will be displayed in the formula bar. 
• Using Excel Now Function in to the following ways :
• The syntax for the NOW function is :

=NOW () -

The NOW function takes no arguments,

• Click on cell C5 - the location where the results will be displayed, 
• Click on the Formulas tab. 
• In the Function Library group, click the Data & Time icon to open the function drop down list. 
• Click on NOW in the list to bring up the Foundation Arguments dialog box.  You will see the =NOW () displayed in the cell C5 as well as in the formula bar. 
• Click OK. 
• The current time and data should appear in cell C5. When you click on cell C5 the complete function =NOW () appears in the formula bar.