=(A2-A1)/A1
Format as percentage

     =============================================================
     About percentages in Excel

     Niek Otten, July 26 2006

     In Excel, percentages are stored as fractions; 15% is stored as 0.15, 100% as 1. That makes it easy to calculate with; just
multiply a number with a percentage and you get what you need. No need to divide/multiply by 100. In fact, if you see a
calculation with percentages which has the number 100 somewhere in the formula; be very careful, it might be wrong or at least use
percentages in a way they weren't meant to be used in Excel.
     The conversion to a fraction happens automatically if you enter the % sign: if you enter "15%" (without the quotes) the
value will be 0.15 and it will be displayed as 15%. If you then enter 12 in the same cell, two things can happen: It will be the
number 12 or 12%. What happens in your case depends on a setting:
     Tools>Options, Edit tab, "Enable automatic percent entry" (only Excel2000 and newer).
     All built-in functions of Excel and all the functions in Analysis Toolpak use this representation of percentages: be careful
when supplying parameters to these functions; never use whole numbers (like 8), always use fractions (like 0.08 or, even better,
8%).

     Frequently Asked Questions:

     Q:
     I have A1 and B1. How do I get C1 to show B1 as a percentage of A1?
     A:
     Formula in C1: =B1/A1, Format as %

     Q:
     I have A1 and B1. How do I show the difference as a percentage in C1?
     A:
     As a percentage of A1: =(B1-A1)/A1, Format as %
     As a percentage of B1: =(B1-A1)/B1, Format as %
     =============================================================

If A1 was old price, A2 new price then the increase was A2-A1 ( £23)
The ratio of change/old price is =(A2-A1)/A1 (23/134 = 0.171642....)
A percentage is nothing more than this ratio multiplied by 100   (17.16 )
but with calculators/computer all we need to is push the % key - or in
Excel, format as Percent.
to get 17.16%

We say the price has risen by 17%.
Note that =(A2-A1)/A2 gives 14.65%. The item was 14% cheaper then compared
to now.

The (  ) are need to make Excel subtract before it divides - the thing it
wants to do first!
best wishes

How would you figure out the percentage increase on paper? When you figure
that out, you can use the same method in Excel.

Tyro

thanks guys