vulgar fraction 
noun British
A fraction expressed by numerator and denominator, not decimally.Oh, the wonders of Euroland, the rip-off merchants can no longer hide behind the vulgar fractions of currency translators....
- Where once we could hide behind the average tourist's weakness with vulgar fractions, a Spanish visitor could say to me in the pub the other night, ‘this pint I am holding in my hand is twice the price it is in Barcelona.’
- To indicate vulgar fractions (23 / 24 for twenty-three twenty fourths) and ratios (miles/hour for miles per hour).