Any power of 5 when divided by 4 gives a remainder 1.
Here, the power of 3 is itself a power of 5 and will give the remainder of 1 when divided by 4.
The last digit of the number will be 3.
And, hence, the last digit of the given number is $3+1 =$ 4.
Edit: For a detailed alternative solution, check comment by Deepak.
Edit 2: For yet another alternative solution, check somment by Sravan Reddy.