網址: https://static.vecteezy.com/system/resources/previews/014/441/063/original/number-4-with-blue-purple-gradient-color-and-black-outline-vector.jpg
網址2: https://es.vecteezy.com/arte-vectorial/14441063-vector-numero-4-con-color-degradado-azul-purpura-y-contorno-negro
