Example of a ring without unity that has a subring with unity?
106894
If a subring of a ring R has identity, does R also have the identity?
12110
How are $2\mathbb{Z}\ncong3\mathbb{Z}$ different as rings?
21604
A complete ring with respect to an ideal
127030
Simple example of non-arithmetic ring (non-distributive ideal lattice)
65091
Subring which is not an ideal?
143051
Inverting noninvertible elements in a bigger ring.
11573
Rings and some of their properties
114329
Example of subring that is not an ideal
153852
Example of modules that are projective but not free; torsion-free but not free
86724
Example of a non-zero module that has no associated primes
48480
Find two elements that don't have a gcd in a subring of Gaussian integers
112560
Simple Noetherian domain which is not a division ring
18003
Standard example where Jacobson radical not equal nilradical
94203
Examples for almost-semirings without absorbing zero
131460
Example of finite field extension where root not separable
77112
Artinian rings that are not Artin algebras
91129
Can there be an onto homomorphism from a ring without unity to a ring with unity?