Functions
Pre defined Formula. User has to remember the name, purpose and syntax of the function.

syntax of any function:
=funcName(list of arguments)

Arguments are the values on which function has to work.

arguments of function can be numbers, cell addresses or cell range

all the arguments of a function are enclosed between pair of parenthesis as each one is separated with comma.

with single argument Excel can refer many cells when the argument is a cell range.

Eg:
=SUM(3,5,6)
=SUM(A5,B8,C10)
=SUM(A1:A10)
=AVERAGE(A1:A10)

There are 10 groups of functions in Excel.
All the functions can be seen from:
Formulas Tab–>Functions Library

Types of functions in Excel based on their number of arguments:
1. no arguments Eg:=TODAY()
2. many arguments (Maximum :255) Eg: =SUM(A4,B7,C10:E23)
3. limited arguments Eg: =IF(A1>10,”True”,”False)

type of arguments in the syntax of function:
bold letters: compulsory arguments
[]: optional arguments
….: many arguments (max. 255) can be supplied

Ways to Enter a function:
directly type the function
(or)
select the function from Functions Library of Formulas Tab
(or)
using Insert Function Button (Shift+F3)