Latest TCS Aptitude Question SOLUTION: unit digit in 4^5^6^7^8^9

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(#M40026344) TCS Numerical Ability question Keep an EYE

unit digit in 4^5^6^7^8^9

Asked In TCS abhishek mishra (10 years ago)

Solved Neha Jha Read Solution (20)

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Read Solution (20) :

Neha Jha  (10 years ago)

unit digit should be 4
as 5^(any no.) would have unit's digit as 5
4^(any odd no.) would have unit's digit as 4
ie.4^5^6^7^8^9=4^(any no.ending in 5)=4^(...5)=4^(any odd no.)=4

Is this solution Helpfull? Yes (118) | No (19)  

harshu  (10 years ago)

(4) its power can be multiplied by rule (x)^n^m gives (x)^m*n
ie 5*6*7*8*9 gives an even no
and
4^1 : gives 4 at unit digit
4^2 :6 at ud
4^3 gives 4 at unit digit
therefore when power is odd unit digit is 4
and when poer is even unit digit is 6
hence ans. is 6

Is this solution Helpfull? Yes (29) | No (14)  

Heena Jain  (10 years ago)

unit digit will be 6
4^(odd)=6 and 4^(even)=4

Is this solution Helpfull? Yes (14) | No (28)  

Heena Jain  (10 years ago)

sory i made a mistake
4^(odd)=4
and 4^(even)=6
unit digit will b 6

Is this solution Helpfull? Yes (11) | No (4)  

ritabrata gautam  (10 years ago)

GUYS THE CORRECT ANSWR IS 6 ... HOW???
4^odd=4(unit digit)...4^even=6(unit digit)....6^any=6(unit digit)....
1st step ...4^5=4(unit digit) now expression 4^6^7^8^9....
2nd step ...4^6=6(unit digit) now expression 6^7^8^9.....now as 6^any=6(unit digit)..so ans will be 6

Is this solution Helpfull? Yes (9) | No (4)  

Prakash kumar  (10 years ago)

WE KNOW m^n^o = m*n*o
similarly , 5*6*7*8*9 = ---0 i.e. last digit will be 0 (5*6 =30)
it means 4^even
so last digit is 6.

taking sense of 5 as power and calculating is wrong becoz of m*n*0 rule

Is this solution Helpfull? Yes (5) | No (1)  

kamal behl  (10 years ago)

ans=6
4^odd=4
4^even=6
6^even or odd ans should be 6.............

Is this solution Helpfull? Yes (5) | No   

shikha gupta  (10 years ago)

ans : 4 by cyclicity rule.. 4^1 = 4

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

shaurya gupta  (10 years ago)

look friends it is just simple to make it up

if any EVEN number has a power with a MULTIPLE of 4 then its unit digit is ALWAYS 6

here:- 4^5^6^7^8^9 =4^(5*6*7*8*9)
=4^15120 (multiple of 4)
=unit digit is 6

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

swati singh  (10 years ago)

unit digit is 0
as 5 multiplied with any no. gives 0 as the unit digit

Is this solution Helpfull? Yes (3) | No (19)  

Sahil  (10 years ago)

unit digit 4

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

Rohan Goyal  (10 years ago)

answer is 4...

Is this solution Helpfull? Yes (2) | No (1)  

Jaswanth Kokkiripati  (10 years ago)

unit digit is 6

Is this solution Helpfull? Yes (2) | No (1)  

abhishek mishra  (10 years ago)

@swati-5*3=15..where is zero???

Is this solution Helpfull? Yes (1) | No (2)  

Aastutee sahu  (10 years ago)

as cyclicity of 4 is 4
so 4^1=4

Is this solution Helpfull? Yes (1) | No (4)  

mehar mani linga  (10 years ago)

i agree with u neha
unit digit must be:4

Is this solution Helpfull? Yes | No (1)  

ravendra tiwaree  (10 years ago)

can anyone pls tell me the correct answer?

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sagar  (10 years ago)

as,4^9! is even,so unit digit is 6...

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tejomay saha  (10 years ago)

unit digit shuld be 4 like short cut way=4^5^(6^7^8^9) as 5^x=unit digit always 5 so 4^5 now 4 's unit digit may be 4,6 so 5/2 remaindr=1 then 4

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aditi bose  (10 years ago)

5*6*7*8*9= 15120 which is an even number.. 4^even number has 6 in the units place so ans will be 6

Is this solution Helpfull? Yes | No (1)  

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