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 ab.


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.


For each test case output an integer per line representing the result.


3 10
6 2

Output: 9 6

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softxide: 2017-08-10 13:33:02

you can easily do the solution in O(4) space and O(4) time if you keep track of pattern in last digit .
Furthermore problem says a and b cant be zero , but there are test cases as per range if a and b .

larunrahul: 2017-07-04 18:21:58

Hint: The pattern repeats for every 4 powers of last digit of 'a'. Such a simple but tricky one. Observe the pattern.

manish_nit97: 2017-06-30 21:03:50

power function will not work here. a^b can't be dealt with primitive data types. Use mathematical properties and that's it!!

heybob: 2017-06-28 20:55:48

Can someone explain the procedure to solve it without pow(). THanks

coder_at_work: 2017-06-26 07:56:13

Your source code shouldn't occupy more than 700 bytes, so remove unnecessary header files, whitespace etc. Easy problem, try to observe pattern. No need of using pow() function.

ak_cruiser: 2017-06-21 02:07:32

reduce the size of code by eliminating comments and whitespace to avoid size limit.
for those who are getting wrong answer even if the solution is correct try it by avoiding POW function

cammy_0605: 2017-06-21 00:54:45

my solution is totally correct but when i submit it says your solution is too big, exceeds 700 bytes limit

themast3r: 2017-06-17 01:31:10

Keep in mind that both base as well as the index can be zero, coasted me 1 WA.

himanshu_12345: 2017-06-07 13:46:32

can anyone tell what does it mean of WA

Jamil Siam: 2017-05-31 11:47:35

Bigger constraints:

Added by:Jose Daniel Rodriguez Morales
Time limit:1s
Source limit:700B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: GOSU