▁t ilt ed , ▁the ▁number ▁" 5 0 " ▁on ▁the ▁bottom ▁left ▁corner ▁of ▁the ▁note ▁displays ▁an ▁effect ▁of ▁the ▁light ▁that ▁moves ▁up ▁and ▁down . ▁The ▁number ▁" 5 0 " ▁also ▁changes ▁colour ▁from ▁emer ald ▁green ▁to ▁deep ▁blue . ▁ ▁Security ▁Thread : ▁When ▁the ▁note ▁is ▁held ▁to ▁the ▁light , ▁the ▁security ▁thread ▁appears ▁as ▁a ▁dark ▁line . ▁The ▁" € " ▁symbol ▁and ▁the ▁value ▁of ▁the ▁note ▁can ▁be ▁seen ▁in ▁tiny ▁white ▁letter ing ▁in ▁the ▁stri pe . ▁ ▁Micro print ing : ▁Some ▁areas ▁of ▁the ▁bank note ▁feature ▁a ▁series ▁of ▁tiny ▁letters . ▁The ▁micro print ing ▁can ▁be ▁read ▁with ▁a ▁magn ifying ▁glass . ▁The ▁letters ▁are ▁sharp , ▁not ▁bl ur red . ▁ ▁Cir cul ation ▁▁ ▁The ▁European ▁Central ▁Bank ▁is ▁closely ▁monitoring ▁the ▁circul ation ▁and ▁stock ▁of ▁the ▁euro ▁co ins ▁and ▁bank notes . ▁It ▁is ▁a ▁task ▁of ▁the ▁Eu ros ystem ▁to ▁ensure ▁an ▁efficient ▁and ▁smooth ▁supply ▁of ▁euro ▁notes ▁and ▁to ▁maintain ▁their ▁integrity ▁throughout ▁the ▁euro ▁area . ▁ ▁In ▁May ▁ 2 0 1 9 , ▁there ▁were ▁ ▁€ 5 0 ▁bank notes ▁in ▁circul ation ▁around ▁the ▁Euro zone . ▁for ▁€ . ▁ ▁This ▁is ▁a ▁net ▁number , ▁i . e . ▁the ▁number ▁of ▁bank notes ▁issued ▁by ▁the ▁Eu ros ystem ▁central ▁banks , ▁without ▁further ▁distinction ▁as ▁to ▁who ▁is ▁holding ▁the ▁currency ▁issued