This is one of the most simple excel formula
SUM - used to add numbers
SYNTAX: =SUM(NUMBER1,NUMBER2,.................NUMBERn)
Each number can be specified in cells and in the systax number1 = cell
eg: = sum(A2,B3,D1) will add the numbers in these cells
You can also use combination of numbers annd cells
eg: =SUM(8,C3) will add the number in cell C3 to 8
You can also specify ranges in this formula
eg: =SUM(A6:I6) will add numbers in cells A6,B6,C6,D6,E6,F6,G6 and I6
Now you can use a combination of all above
eg: =SUM(E4:E9,C3,8,H3:I5,2,7)
Here we have added 2 ranges, one cell and 3 numbers.
Such a simple formula with so many combinations possibel makes SUM formula very useful in excel