Invalid Argument: Unable to Sum a Column

I am trying to sum one of my columns, but I get an error saying the argument is invalid. I am allowed to count the base column, but each row has a value ranging from 1-30 (and it counts each row as 1 no matter what). I was wondering if there was a way to sum these rows?

Hey Zachary!

It looks like your Quantity column is a string data type! If you would like to sum up these values then you will have to convert this to a numeric column!