Q13 of 123 Page 3

For the binary operation multiplication modulo 5(×5) defined on the set S = {1, 2, 3, 4}. Write the value of (3 ×5 4–1)–1.

From the definition of multiplication modulo

a*b = (m is the base of the modulo)


Here the base is 5 and the set is S = {1,2,3,4}


So, we can make a composition table as :-



The identity element is 1.


The inverse element of 4 is 4 itself.


∴ (3 4-1)-1 = (3 1) -1 = 3-1 = 2.


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