In article ,
Al Reynolds wrote:

You will think that I am slightly sad for having noticed
this, but on pondering the 13.5% extra free offer on some
beer cans, I realised that:
440ml + 13.6% = 500ml (0.5 litre)
500ml + 13.6% = 568ml (1 pint)

I can't believe this is a coincidence.

Didn't they used to do the old quietly_reducing_the_size
trick with chocolate bars as well?

--
Tony Williams.