Click A16. Type '='
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Click the Formulas tab.
Click the button (Financial, Logical, Text, Date & Time, Lookup & Reference,
Math & Trig, More Functions, or Recently Used) from the Function Library
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Click a submenu if necessary.
Then click the function to insert into a formula.

Excel inserts the function you selected into the formula bar with a set of parenthesis.
And opens the Function Arguments dialog box.
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Type the argument or select the cell or range you want to insert in the function.

Press Enter to finish the input.
