6636 has 3 circle so 6636=3
8118 has 4 circle so 8118=4
2212 has 0 circle so 2212=0
8688 has 7 circle 8688=7
5971 has 1 circle 5971=1
I don’t think so, a graph is a function only if the vertical line passes through the graph at one distinct point.
But I’m not exactly sure cus I’m still learning geogebra