Latest TCS Aptitude Question SOLUTION: What is the unit’s digit of 21^3 *21^2*34^7*46^8*77^8 ?

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What is the unit’s digit of 21^3 *21^2*34^7*46^8*77^8 ?

Asked In TCS shikha panwar (9 years ago)

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susmita dutta chowdhury  (9 years ago)

1*1*4*6*1=24
so unit digit=4

Is this solution Helpfull? Yes (37) | No   

Arshad Juned  (9 years ago)

21^3 = 1 ( always 1 )
21^2 = 1
34^7 = 4 ( 4 6 4 6 4 6 4 ...)here 7 is odd. so, it will be 4 in unit place
46^8 = 6 (always 6 will be in unit place)
77^8 = 3 ( 7 9 3 1 7 9 3 1...)

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

Arshad Juned  (9 years ago)

21^3 = 1 ( always 1 )
21^2 = 1
34^7 = 4 ( 4 6 4 6 4 6 4 ...)here 7 is odd. so, it will be 4 in unit place
46^8 = 6 (always 6 will be in unit place)
77^8 = 3 ( 7 9 3 1 7 9 3 1...)

1*1*4*6*1=24 = 4 in unit place
ANS = 4

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

Diwakar kumar  (9 years ago)

in these type of problem take only unit digit and solve the problem.
21^3=1^3=1
21^2=1^2=1
34^7=4^7=16*16*16*4=6*6*6*4=36*24=6*4=24=4
46^8=6(any power of 6 wll always gives us 6)
77^8=7^8=49*49*49*49=9*9*9*9=81*81=1*1=1
now multiply all results
1*4*6*1=24=4(unit digit is 4) ANS.

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abhe chandu  (9 years ago)

21^3=unit digit is 1^3=1
21^2 is 1
34^7 which is 4^7=according to fourth table 4*1=4,4*4=16,4*4*4=64 hence unit digit repeated is 4 and 6 so divide 7/2 we get rem as 1 s0 4^1 is 4.
46^8 always the unit digit is 6.
77^8 is 1.
1*1*4*6*1=24 ans is 4

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cdude  (9 years ago)

unit digit of 21^3 = 1
unit digit of 21^2 = 1
unit digit of 34^7 = 4
unit digit of 46^8 = 6
unit digit of 77^8 = 1

hence 1*1*4*6*1 = 24 unit digit is 4

ans is 4

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jagriti goomer  (9 years ago)

ans:4
last digit of 21^3=1
last digit of 21^2=1
last digit of 34^7=4
last digit of 46^8=6
last digit of 77^8=1

so 1*1*4*6*1 gives 1 as unit digit

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vishwas  (9 years ago)

unit dig :
21^5 =1
34^7 =4
46^8 =6
77^8 =1
1*6*4*1=4(ans).

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anitha.p  (9 years ago)

unit digit:1*1*4*6*6=144
Ans=4

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latika  (9 years ago)

4
1*1*4*6*1

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Madhur Rusia  (9 years ago)

21^3*21^2 = 21^5 unit digit 1
34^7 unit digit 4
46^8 unit digit 6
77^8 unit digit 1
product of all unit digits 24
hence unit digit is 4

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ramesh  (9 years ago)

1*1*4*6*1
4

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sindhureddy  (9 years ago)

1*1*4*6*1=24 units place is 4

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