Latest TCS Aptitude Question SOLUTION: All even numbers from 2 to 98 inclusive, except those ending in 0, are multiplied together what is the rightmost digit (the units digit) of the product? a) 0 b) 2 c) 4 d) 6

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(#M40040718) TCS Numerical Ability question Keep an EYE

All even numbers from 2 to 98 inclusive, except those ending in 0, are multiplied together what is the rightmost digit (the units digit) of the product?

a) 0
b) 2
c) 4
d) 6

Asked In TCS purva (9 years ago)

Solved yash upadhyay Read Solution (14)

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Narasapu Hari prasad  (9 years ago)

ans is 6
first multifly all numbers ending with 2 those are 2*12*22*32*42.......*92=2^10=4 is last digit
multify all numbers ending with 4=4^10=6 last digit
multify all numbers ending with 6=6^10= 6 last digit
multifly all numbers ending with 8=8^10=4 last digit
so 4*6*6*4=6 last digit

Is this solution Helpfull? Yes (37) | No (7)  

yash upadhyay  (9 years ago) Best Solution

2^10 * 4^10 * 6^10*8^10 = 2^70 * 3^10
2^2 * 3^2 = 36
i.e. ans is = 6

Is this solution Helpfull? Yes (24) | No (4)  

Abhijit Das  (9 years ago)

2*4*6*8 UNIT DIGIT 4---- ------->1
12*14*16*18 UNIT DIGIT 4----->2
22*24*26*28 UNIT DIGIT 4----->3
---------
92*94*96*98 UNIT DIGIT 4------>10
SO 4^10 UNIT DIGIT 6.. AS 4^N GIVES UNIT DIGIT 4 WHEN N IS ODD AND GIVES UNIT DIGIT 6 WHEN N IS EVEN

SO ANS -->6

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manish sukhadia  (9 years ago)

2^10 * 4^10 * 6^10 * 8^10

2^10 (1 * 2 * 3 * 4) = 2^10 * 24

1024 * 24 = _____6 so that 6 is unit digit

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

Niranjan Kumar  (8 years ago)

2^10=1024........unit digit of right side is 4
4^10=1048576....unit digit of right side is 6
6^10=60466176.....unit digit of right side is 6
8^10=1073741824...unit digit of right side is 4
so 4*6*6*4=576....unit digit of right side=6

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vijay  (9 years ago)

4 ans .......................

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Pritam Nandi  (9 years ago)

ans will be 0 . because from 2 to 98 there are so many numbers whose unit digits are 2 and 5 ... if we multiply those numbers the unit digits will be 0 . now a no having unit digit 0 is multiply with any number gives the result having unit digit 0 ....

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Debashish Deka  (9 years ago)

(2^10) * (4^10) * (6^10) * (8^10)
= 4 * 6 * 6 * 4 (unit digit for 2^10 is 4 ...similarly unit digit for 4^10 is 6 etc. )
= 6 (final unit digit)

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Lakshmi Narayanan.k  (7 years ago)

It is very simple.
2,4,6,8 the product of this numbers gives the unit digit of 4
similarly 12,14,16,18 gives unit digit of 4.
4*4*4*4*4*4*4*4*4*4 gives the unit digit of 6. 6 is the correct answer

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SOUVIK PURKAIT  (9 years ago)

2 ans

(2*4)=8

6*8*12*14**16*18*22*24**....98 --> last digit 4

overall last digit= 8*4 --> 2

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prashansa  (9 years ago)

ans should be 4 because digit can be end with 2,4,6,8 only so 4

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ritesh  (7 years ago)

2 4 6 8
12 14 16 18
20 24 26 28
.
.
.
.
92 94 96 98

2*4*6*8 (=384) at units place for one set of four number in the table is multiplied and total 10 time such multiplication will take place
ie 384*384*384...10times ie 384^10

cylicity of 4 at unit place means it end with 4 or 6 when even power its 6

thereofre 6

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sourabh rai  (9 years ago)

2*4*6*8*12*14**16*18.............98
so the unit digit is 4.
ans. 4.

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Arpan Ghoshal  (5 years ago)

I don't know but it seems the answer is 0

Just run this code in java..

import java.math.*;

public class MyClass {
public static void main(String args[]) {

BigInteger a=new BigInteger("1");

for(int i=2;i

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