Aptitude - Numbers - Discussion

How do define unitdigit. Explain?

Unitdigit in 7^95 is 3 and unit digit in 3^58 is 9

So the answer shoudld be 6.

Then how come 4 is the answer, I didnt get.. please explain

Remember One thing first....As we are finding the Units digit
We are concentrated on (NUMBER =0 to 9 .)

And (NUMBER)^(K)....when K/4 remainder=0 then
Units digit value = NUMBER^0


IF (NUMBER)^(K)...when K/4 leaves some remainder ...then
Units digit value= NUMBER^remainder

REMEMBER THAT REMAINDER IN THESE CASES IS BETWEEN 0 to 3..SO
THERE IS NO PROBLEM IN FINDING POWERS...


AS we are done with the things that need to be understood lets dig into the problem .

FIRST ...7^95..........95/4 remainder is 1 so units digit will
be 7^1=7

SECOND....3^58.......58/4 remainder is 0 so units value is
3^0=1

SO DIFFERENCE IS 7-1=6 WHICH IS THE ANSWER.


CORRECT ME IF I AM WRONG

EVERYTHING THAT I EXPLAINED WAS RIGHT ..BUT I UN NOTICINGLY DIVIDED 95/4 whose remainder is 3

and 58/4 remainder is 2

so 7^3=343 and 3^2=9
and the difference is 343-9 where there 334.

So 4 is the answer.

7^3=343 and 3^2=9
difference 343-9
ans 4
How? Please explain every step.

Idea is simply to express the given number, in such a way that unit's place should be 1. i.e., 7^4 is 2401 and 3^4 is 81.

I want to correct you. We are not finding the absolute value of the question. 3-9 = 6 is not the answer as it is -6 and you people don't know the concept of negative remainders and modulo. So the answer 4 is absolutely right.

Hi guys,

Here the concept is ultimately to make 1 as base so that 1 power anything will be one only.

7^95 = (7^2)^47 X 7 = 9^47 X 7 = ((9^2)23) X 7 X 9 = 1^23 X 63 = 63 (Remember here I am only considering nit digits).

Same as calculate for 3^58 it will be 9, so the answer is 63-9 = 54 = 4 (Unit digit).

Unit digit should not show in negative digits. So actually total digit in 7^95 is 343.43-9=34.

So 4 is the correct answer.

My answer is 6. But how is it 4? Please elaborate clearly.