"1/4 finals" is read quarterfinals. But what about "1/8 finals"? How do you say that?
But I saw it on the official website for London 2012.
I vaguely recall noticing that on the London 2012 website now. It's very uncommon. The descriptions of the rounds normally go (using a tennis tournament starting with 64 entrants as an example):
Round of 64
Round of 32
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.