Excluded from a group chat?

[Julie]

So two months ago for Halloween all of my friends and I hung out. Then, they all started handing out without me and 2 other people a lot (like almost every weekend- I see the pictures on social media). There was one girl that I did not know well (I didn't have her number) but there were also ten that I have known for a pretty long time. They also made a group chat without me, but I heard that the one who made it was the girl whose number I did not have. Yesterday we all hung out, including me and the 2 people that went to Halloween but weren't invoted to anything else. Is there any way that I can politely ask to be in the group chat?