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
janakiram_18: 2019-11-22 03:55:27

Modular exponentiation is throwing a TLE and i'm doing it in python

apshada: 2019-11-10 09:56:11

its just (a^b)mod 10

purplecs: 2019-10-06 12:18:11

use binary exponentiation

pyskmr: 2019-10-02 15:12:33

use fast exponentiation.

jitto777: 2019-09-13 06:42:50

good question though..

itsmysyntax: 2019-08-03 20:23:22

@ghazikhan13 to get last digit . for example do 346 %10 and your output will be 6

rikilg: 2019-07-19 15:23:43

Source limit exceeded ;-)
be careful with the digit 0
AC in 2 go's!

ghazikhan13: 2019-07-17 13:17:46

hey guys, can anyone tell me why everyone did modules division by 10 only, why not any other number ??

Last edit: 2019-07-17 14:08:23
scolar_fuad: 2019-07-09 05:46:21

Just think like Big_Mod algorithm i or find pattern you will get answer

sanket17: 2019-07-08 11:05:21

For all those who are getting WA after considering a=0,b=0 case also its due to pow() function here input is non_primitive so we cant use pow function it will not return the required value

PS: even i dont how we can know input is primitive or non primitive if somebody know pls tell me also

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