# EXCEL
### Using Formulas
A formula can be a combination of
values (numbers or cell references) and mathematical operators into an algebraic
expression. Mathematical operators include the following symbols:
+
for addition
- for subtraction
* for multiplication
/ for division
% for percentage
^ for exponentiation (powers)
In addition you can use parentheses
and decimal points, where needed.
Excel requires that EVERY formula
begin with an equal sign (=). If you just type without this symbol, Excel treats
the entry as text.
Formulas
can be a combination of built-in functions and your own formulas. You can
either pick one of the built-in formulas that have already been defined or
construct your own formula to obtain the same results.
If you wanted to find the average of the values in the cells A2 to A10
you could do this several ways:
= (A2 + A3
+ A4 + A5 + A6 + A7 + A8 + A9 + A10)/9
= SUM
(A2,A3,A4,A5,A6,A7,A8,A9,A10)/9
= SUM
(A2:A10)/9
= AVERAGE
(A2,A3,A4,A5,A6,A7,A8,A9,A10)
= AVERAGE
(A2:A10)
These
formulas would all give the same result if all the cells contained values but the easiest one to type is probably
the bottom one. It is also safer to
use the AVERAGE function as that calculates how many values there are in the
range you select, using =SUM(A2:A10)/9 would lead to an error if one of those
cells was intentionally a blank row as you may only have 8 actual values in that
range.
You can also
start a formula by clicking the = symbol to the left of the white formula bar
box to start the formula wizard.
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