This is a flexible calculation, used in work environments, which can be applied to all manner of things which will make ones day easier.
eg. How much time to take off work for an hour's lunchtime meeting (in this case, 6 hours)
It can also be applied to how many fucks to give.
eg. This client bores me. I would normally try my best but, by careful application of the Bradfield Permutation, it turns out I give zero fucks.
I've got a lunchtime meeting today with a client. It's only an hour but, by applying the Bradfield Permutation, I can roll in any time after 3pm.