Latest TCS Aptitude Question SOLUTION: unit digit of 124^123!

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(#M40026384) TCS Numerical Ability question Keep an EYE

unit digit of 124^123!

Asked In TCS Kunal Verma (10 years ago)

Unsolved Read Solution (18)

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Read Solution (18) :

Amisha Agarwal  (10 years ago)

ans:6
as 123! is in form of 4n

Is this solution Helpfull? Yes (37) | No (10)  

chaitu   (10 years ago)

4^even power=6

Is this solution Helpfull? Yes (14) | No (4)  

pankaj verma  (10 years ago)

ans is 4.
sol-
124^(123!)= 124^123+124^122+124^121+......124^1
=sum of unit digit of all terms
= 4+6+4+6+4+6+.......+4
= 10*61+4
= 614
hence ans is 4.

Is this solution Helpfull? Yes (13) | No (28)  

Rahul Kumar Mehta  (10 years ago)

unit digit is 4

Is this solution Helpfull? Yes (10) | No (14)  

deepika choudhary  (10 years ago)

unit place 6

Is this solution Helpfull? Yes (9) | No (3)  

rupal sharma  (10 years ago)

i think its 4.. 123! last 2 digits are 00 that's why divisible by 4 .. so no reminder left .. so its 4

Is this solution Helpfull? Yes (4) | No (12)  

Swarnali Biswas  (10 years ago)

unit digit is 4

Explanation:
For this type of problem, remember the following steps :

1> look at the unit digit of 124 = 4
2> 4^1=4 ,4^2=16,4^3=64,4^4=256.....so on.. Here,we can see that we get the sequence of 4,6,4,6,....as the unit digit repeatedly after 2 times .
3> Now,divide 123%2=1(get the remainder as 1)
4> 4^1=4

Is this solution Helpfull? Yes (4) | No (3)  

salil  (10 years ago)

u donno a SHIT.TO THOSE GUYS WHO IS SAYNG 4...FIRST GET UR FACTS STRAIGHT.ITS 6...OPEN CALCULATOR and do the miracle.idiot

Is this solution Helpfull? Yes (4) | No   

Anay Das  (10 years ago)

123! contains many 0' at the end...so 123! is a even number..so,,if we think
124 ^ even..then unit digit is 6 because 4's cycle is like 4,6,4,6,4,6.

Is this solution Helpfull? Yes (4) | No   

Guru Pranav  (10 years ago)

4 TO THE POWER EVEN WILL BE ALWAYS 6 !!!

Is this solution Helpfull? Yes (3) | No (2)  

GURU CHARAN M S  (8 years ago)

It is not soo complex as many of them explained. Remember factorial of all the numbers except 1 is always even. and four raised to ever number always ends with 6. so ans is 6.

Is this solution Helpfull? Yes (1) | No   

ARISH KHAN  (8 years ago)

I have a simplest way

we have 123!
Now take last two Digit of the Number is 23!
now divide it by 4...
23!/4= Remainder 3 right
then find 3!
we know the 3! is 6 so Ans is 6.

Is this solution Helpfull? Yes (1) | No   

joydeb  (8 years ago)

2
as123=4n+3
for ! unitdigit*7,,,
here6*7
so unit digit =2

Is this solution Helpfull? Yes | No (3)  

Soumyadip Chowdhury  (8 years ago)

Ans is 6
because we just need to calculate 4^123!
and 123! trailing more than two zeroes...
then just dividing last two zeroes by 4, the rem=0 i.e the last digit of the cycle i.e 4..
so 4^4 is 256...
so the last digit is 6..

Is this solution Helpfull? Yes | No   

Somnath Biswas  (8 years ago)

4^3=64
unit digit 4

Is this solution Helpfull? Yes | No (1)  

Surendra Gangisetti  (8 years ago)

4^even power=6 and 4^odd power=4.

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janmanjay banerjee  (8 years ago)

123/4=30+3 so for odd places unit digit is 4
ANS =4

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AKRITI SRIVASTAVA  (8 years ago)

(124)^123!=(31*4)^123!
31*4=124
hence Unit place is 4

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