How 9 Cheenta students ranked in top 100 in ISI and CMI Entrances?

Learn More(a) 1

(b) 2

(c) 3

(d) 4.

First, ask yourself how many groups are there of order 4.

the answer is simple => Z/4Z and Klein’s four group (K).

So intuitively there should be two rings with 4 elements.Okay, I will give you two rings or same order=> (R,+,.), (R,+,*) . see that order of the rings are same but I have changed the multiplication, and

I define a*b=0 for all a,b in R. [(R,+,*) is called zero ring]

Hint 3:Question: Prove that (R,+,.) and (R,+,*) are not isomorphic! (easy) So, we had (Z/4Z,+,.) and (K,+,.) as our answers. But if you change the multiplicationHint 4:

to “*” then there will be 4 different rings

*upto isomorphism* right? Hence the answer is 4.

Bonus Problem:

Prove that there are only two non-ismorphic p-rings(ring with p elements) upto isomorphism.

The higher mathematics program caters to advanced college and university students. It is useful for I.S.I. M.Math Entrance, GRE Math Subject Test, TIFR Ph.D. Entrance, I.I.T. JAM. The program is problem driven. We work with candidates who have a deep love for mathematics. This program is also useful for adults continuing who wish to rediscover the world of mathematics.

Cheenta is a knowledge partner of Aditya Birla Education Academy

Advanced Mathematical Science. Taught by olympians, researchers and true masters of the subject.

JOIN TRIAL