Old Drag Racer Formulas: The "Q" Ratio or Factor??

Here's one I used to use from days gone by....
If you made a pass that was compromised in some way (spun the tires, or lost fuel pressure at the 1000' mark, etc.)
take 1320 and divide your ET to get MPH, OR divide MPH to get your ET.
example: 1320/108 = 12.22 (ET) , or 1320/12.22= 108 (MPH) its real accurate in the 12 sec range, but it's not as accurate for faster cars.. fun to play with, easy to remember.