How to figure out your memory bandwidth

Whelp, Maximum PC did a comprehensive video card guide in their new magazine. The coolest thing I found was how to figure out your memory bandwidth. I'll use my radeon 9500 pro as a example.
Take the bus bit rate: 128bit
Take the DDR speed: 270mhz
Multiply by 2
then divide by 8
128*270*2= roughly 70,000gb now divide that by 8 and we have 8.6gb. I want to oc my mem to 325 now =)
Have fun

well what your doing is converting your bit rate into bytes...this multiplied by the amount of times it can send across this bus a second would give the theoretical maximum bandwidth

128 = 16bytes as 256 would be 32bytes...multiply either of them by the clock

just incase your unsure what the bus's width has to do with getting to the final bandwidth in GBs