er Vs liang

what is the difference between, two, er and two, liang. I hear Liang Dian a lot I have been told it is correct and I've been told it is incorrect. To me Liang Dian is the same as saying " a pair O'clock" in other words they are not always interchangable !!

er is used in counting. Liang is used when you are talking about two objects.

你们好！ Thank you very much for your explanation Alan! The digit 2 is 二. This is used mainly for numbers and in counting. Often the number are unspecific or abstract. However, if you want to specify quantities (i.e. "two of something") then you need to use 两. 希望这会帮你！I hope this helps! - Lin Ping