Complex sentence: In mathematics, a subring of "R" is a subset of a ring that is itself a ring when binary operations of addition and multiplication on "R" is restricted to the subset, and which contains the multiplicative identity of "R".
Split into simpler sentences: In mathematics, a subring of "R" is a subset of a ring. It is itself a ring with the restrictions of the binary operations of addition and multiplication of "R", and which contains the multiplicative identity of "R".