ve ys ▁had ▁found ▁that ▁ 5 0 , ▁ 2 0 ▁and ▁ 1 0 c ▁co ins ▁were ▁too ▁large ▁and ▁could ▁not ▁be ▁easily ▁carried ▁in ▁large ▁quantities . ▁The ▁original ▁ 5 0 c ▁coin , ▁with ▁a ▁diameter ▁of ▁ 3 . 2 ▁cent imet res , ▁was ▁one ▁of ▁the ▁largest ▁co ins ▁in ▁circul ation ▁world wide , ▁and ▁the ▁original ▁ 2 0 c ▁coin , ▁New ▁Zealand ' s ▁second ▁biggest ▁coin ▁at ▁the ▁time ▁at ▁ 2 . 8   cm , ▁is ▁bigger ▁than ▁any ▁current ▁circul ating ▁coin ▁( the ▁biggest ▁coin ▁in ▁circul ation ▁is ▁the ▁$ 2 ▁coin ▁at ▁ 2 . 6   cm ). ▁ ▁The ▁size ▁of ▁the ▁ 1 0 c ▁piece ▁was ▁too ▁close ▁to ▁that ▁of ▁the ▁doll ar ▁- ▁in ▁fact , ▁it ▁was ▁so ▁close ▁that ▁it ▁was ▁possible ▁to ▁put ▁two ▁ 1 0 c ▁pieces ▁in ▁a ▁par king ▁meter ▁together ▁and ▁receive ▁$ 1 ▁worth ▁of ▁par king ▁time , ▁or ▁jam ▁the ▁meter ▁and ▁make ▁par king ▁free ▁anyway . ▁The ▁advent ▁of ▁pay ▁& ▁display ▁meter ing ▁in ▁larger ▁cities , ▁where by ▁one ▁is ▁required ▁to ▁use ▁another ▁meter ▁if ▁the ▁first ▁one ▁is ▁jam med , ▁has ▁largely ▁stopped ▁this ▁practice . ▁ ▁The ▁prices ▁of ▁co pper ▁and ▁nick el ▁used ▁to ▁mint ▁the ▁old ▁co ins ▁were ▁high ▁and ▁rising ▁ste ep ly , ▁and ▁the ▁metal ▁content ▁of ▁some ▁co ins