The value of 351 mod 5 is  

Q. The value of 3⁵¹ mod 5 is     .

Solution:

= 3⁵¹ mod 5
= (3³)¹⁷ mod 5
= (27)¹⁷ mod 5
= {(2²)⁸*2¹} mod 5
= {(4)⁸*(2)} mod 5
= {(-1)⁸*(2)} mod 5
= {(1*2)} mod 5
= {(2)} mod 5
= 2