▁ ▁Tw enty ▁() ▁is ▁used ▁as ▁a ▁base ▁number ▁in ▁the ▁Wel sh ▁language , ▁although ▁in ▁the ▁latter ▁part ▁of ▁the ▁ 2 0 th ▁century ▁a ▁decimal ▁counting ▁system ▁has ▁come ▁to ▁be ▁preferred . ▁However , ▁the ▁v iges imal ▁system ▁exclus ively ▁is ▁used ▁for ▁ord inal ▁numbers . ▁ ▁means ▁ 2 ▁times ▁ 2 0 ▁i . e . ▁ 4 0 , ▁ ▁means ▁ 3 ▁times ▁ 2 0 ▁i . e . ▁ 6 0 , ▁etc . ▁D au ▁ar ▁by m the g ▁ar ▁d de ug ain ▁means ▁ 5 7 ▁( two ▁upon ▁fifteen ▁upon ▁tw os core ). ▁Prior ▁to ▁its ▁withdraw al ▁from ▁circul ation ▁in ▁ 1 9 7 0 , ▁ ▁( note ▁of ▁six score ) ▁was ▁the ▁nick name ▁for ▁the ▁ten - sh illing ▁(= ▁ 1 2 0 ▁p ence ) ▁note . ▁ ▁Tw enty ▁() ▁is ▁tradition ally ▁used ▁as ▁a ▁base ▁number ▁in ▁Scottish ▁G ael ic , ▁with ▁ ▁or ▁ ▁being ▁ 3 0 ▁( ten ▁over ▁twenty , ▁or ▁twenty ▁and ▁ten ), ▁▁ 4 0 ▁( two ▁tw ent ies ), ▁▁ 5 0 ▁( two ▁twenty ▁and ▁ten ) ▁/ ▁▁ 5 0 ▁( half ▁a ▁hundred ), ▁▁ 6 0 ▁( three ▁tw ent ies ) ▁and ▁so ▁on ▁up ▁to ▁▁ 1 8 0 ▁( n ine ▁tw ent ies ). ▁Now ad ays ▁a ▁decimal ▁system ▁is ▁taught ▁in ▁schools