Why does a US $20 bill have a vertical strip on it when held to light?
Paper money has counterfeit measures to ensure it is very difficult to duplicate/fake
<START_INST>Why does a US $20 bill have a vertical strip on it when held to light?<END_INST><START_CTX><END_CTX><START_A>Paper money has counterfeit measures to ensure it is very difficult to duplicate/fake<END_A>