Hi I'm new to the site, love it so far. I'm racking my brains try to figure out how to decipher a gauge. The patten requires 20sts/24 rows= 4". Size US 7: 16" circular needle. My question is: I have only a size 6: 16" circular needle, I'm not very good in math cuz I can't figure out how many sts for the gauge with this needle. Am I increasing cuz the needle is smaller and if so, how many? When it comes time to cast on it requires 15, am I increasing that too??