Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 108)
108.
What is the unit digit in (4137)754?
1
3
7
9
Answer: Option
Explanation:

Unit digit in (4137)754 = Unit digit in {[(4137)4]188 x (4137)2}

=Unit digit in { 292915317923361 x 17114769 }

= (1 x 9) = 9

Discussion:
18 comments Page 2 of 2.

Aditya said:   1 decade ago
Why it can't be solve like this (4137)^754?

As 7^4 as equal to 1.

Khushi said:   1 decade ago
Please explain how to find unit digit in any problem?

Anki said:   1 decade ago
2^4344 what will be unit digit here?

Fazz said:   1 decade ago
Power = 754.
Divide by 4(7,9,3,1).
754/4 = 2(remainder).

Given number 4137 = 7(last digit).
Last digit^remainder.
7^2 = 49.

Last digit of 49 is 9(answer).

Manish Methani said:   1 decade ago
No dude not always by 4.

4 ka first power = 4 (unit digit 4).
4 ka square = 16 ( unit digit 6).
4 ka cube = 64. ( unit digit 4).
4 ka fourth power = 2401 ( unit digit 1).

4 ka fifth power = now check unit digits later on going to be repeat again. That is 4,6,4,1.

That's why. Unit digit restriction. Is. Upto 4th power in this case

That's why.. Divide the no by 754 by 4.. you will get 2 as a remainder.

By rule ,
Dividend = divisor *quotient +remainder.

Assume quotient = n.

754=4n+2.
n=188.

4137 power 754 = 7 ^ 4 ^188 + 7^2.
=9.

Narasingarao said:   1 decade ago
Is it always that the powers are divided by 4? If yes, kindly explain the concept.

Nav said:   1 decade ago
754 => 4*n + 2, Here n will be 188.

So, unit digit will be the unit digit of 7^2, ie 9.

Rammurti rawat said:   1 decade ago
No need to this question please explain again?


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