It is a binary operation, so, it is closed by definition. It is associative, it contains identity element and actually it has a property that now in general groups need not have namely that it is commutative, but I am not asking for inverses.
तो इसका मतलब यह है कि यह एसोसिएटिव है। इस सेट में आइडेंटिटी एलिमेंट है।