LASTDIG  The last digit
Nestor was doing the work of his math class about three days but he is tired of make operations a lot and he should deliver his task tomorrow. His math’s teacher gives him two numbers a and b. The problem consist of finding the last digit of the potency of base a and index b. Help Nestor with his problem. You are given two integer numbers: the base a (0 <= a <= 20) and the index b (0 <= b <= 2,147,483,000), a and b both are not 0. You have to find the last digit of a^{b}.
Input
The first line of input contains an integer t, the number of test cases (t <= 30). t test cases follow. For each test case will appear a and b separated by space.
Output
For each test case output an integer per line representing the result.
Example
Input: 2 3 10 6 2
Output: 9 6
hide comments
arphox:
20190707 17:07:55
Hint: This can be done in O(1) time, just look for patterns in last digits, they will repeat somehow, somewhere :) 

imambungo:
20190704 17:19:34
thanks sahruz_riyad 

vurise18:
20190627 11:09:29
what data type do we need to store b ? 

ankyy_0103:
20190622 13:40:05
My java Solution is not fitting in source code size . <(^_^)> 

nagrahari:
20190619 10:52:12
nice question 

selfcoder24:
20190612 09:31:04
use modular exponentiation with mod being 10 to fetch last digit. 

kocko:
20190609 18:53:09
Quite stupid requirement for the source code size.... 

motormouthdoda:
20190528 23:12:42
Don't use binary exponentiation. The solution is O(1) 

mubasshir00:
20190521 20:39:42
use Binary Exponentiation. 

sahruz_riyad:
20190520 14:12:36
a and b both are not zero. But separatedly can be zero.. be careful about that Last edit: 20190520 14:13:04 
Added by:  Jose Daniel Rodriguez Morales 
Date:  20081201 
Time limit:  1s 
Source limit:  700B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: GOSU 
Resource:  Own 