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

hide comments
shamimice03: 2016-08-26 13:24:59

is it a big mod realted problem?

narutohokage_1: 2016-08-11 11:14:29

each character is one byte even if it is space. Delete spaces or shorten your variable name . File Size Will BE LESS THAN 700 BYTES.

narutohokage_1: 2016-08-11 11:10:36

Nice Question.

narutohokage_1: 2016-08-11 11:10:19

@vaibhavahuja Try 2 4 (2^4) answer should be 6. If it comes 1 then the mistake you are doing is you take remainder of power divided by 4 . Power%4 but if power is multiple of 4 then power%4 will come to zero so it will always output answer 1 . Check it cost be one wrong answer due to this mistake

narutohokage_1: 2016-08-11 11:03:52

Test Cases
9 0 Output = 1
2 4 Output = 6
9 4 Output = 1

0 0 is not included in test cases as both a and b cannot be zero at same time. But b can be = 0 if a is not zero and vice versa so be sure to check it .

Last edit: 2016-08-11 11:11:30
narutohokage_1: 2016-08-11 11:02:14

Too easy , no need of any technique. Just Check That "2 4" is showing correct as 4%4 = 0 so if you used this approach it will show 2^4 last digit 1 but it is 6. So if pow = multiple of 4 . Then pow%4 == 0 so if pow%4 = 0 change it to 4 then it will show correct answer cost me one wrong answer.

Kartik Singh: 2016-08-10 20:16:26

Last edit: 2016-08-10 20:16:53
coder_hsnake: 2016-08-08 21:03:41

easy one :)

sharath_111: 2016-07-23 16:22:46

good problem for beginners,modular exponentiation :)

cubalgo: 2016-07-22 02:42:28

my 10th..if you r using the pattern then be careful with %0..

Added by:Jose Daniel Rodriguez Morales
Time limit:0.340s
Source limit:700B
Memory limit:1536MB
Cluster: Cube (Intel G860)