Averaging Ads in a spreadsheet

[Guest]

One of the workers here has a spreasheet containing 40 items of different
newspaper ad sizes:

2x4
1x10
6x19.9
2x4
5x13
5x13
4x10.5

Is there a way for excel to determine the average size of ads from the list
above? I tried the Average function =Average(range). Didn't work. I got a
DIV/0 error message. Any help would be appreciated. Thanks

 

[Guest]

=AVERAGE(LEFT(rnga,FIND("x",rnga)-1)*(MID(rnga,FIND("x",rnga)+1,255)))

enter with Ctrl+Shift+Enter

rnga is your range