Aptitude - Numbers - Discussion

Thanks for your clear explanation @Jyothi.

Thanks a lot @Jyothi.

I can't understand it. Please anyone explain me clearly.

Thanks you so much @Jyoti.

Thanks, @Jyoti.

Thanks, @Jyothi. It's an easy way.

@Jyothi.

Thanks for explaining it in easy way.

E.g. 3^200 * 4^500?

Solution :-
3^200 * 4^500.
200/4 = 50, remainder is 0 , 3^4.
500/4 = 125, remainder is 0, 4^4.
= 3^4 * 4^4.
= 81 * 256.
= 1 * 6.
= 6 is the answer.

@Jyothi.

Thanks for your clear explanation.

To find unit digit first we should know the periodic value
ex:-for 2

2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64 and so on.

Clearly observe that unit digit follows a cyclic form i.e after 4 terms it again repeating. So the period of 2 is 4.

Similarly for 3, 7, 8 also same period 4.

For 0, 1, 5, 6 period is always same as itself irrespective of their powers.

So to find a unit digit find the period of that number then divided the power value by the period.

ex: 3^65 period for 3 is 4.

Divide 65 by 4 we get reminder 1.
Now unit digit is 3^1 = 3.
6^59 =6.
7^71 =period for 7 is 4.

Divide 71 by 4 we get remainder 3
7^3 =343 => 3(consider unit digit).
So answer is 3*6*3 = 54 => 4 (unit digit is 4).