Latest TCS Aptitude Question SOLUTION: How many positive divisors of 20020^12 has 7 as their unit digit???

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How many positive divisors of 20020^12 has 7 as their unit digit???

Asked In TCS pre (10 years ago)

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Himanshu  (10 years ago)

first find out the divisors of 20020 i.e comes out to be 4,5,7,11 & 13 then the actual divisors of 20020^12 becomes 2^24,5^12,7^12,11^12 & 13^12 but we want the divisors whose unit digit is 7,therefore we cn get it by 7^1,7^5 and 7*11 thats why the divisors of 20020^12 which is having 7 as there unit digit are (7,16,807,77) therefore 3

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

payaljain  (10 years ago)

ans is 7^1,7^5,7^9
77,77^5,77^9 because it is having 7^12 or 77^12 terms
ans is 6

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ASHISH KUMAR MISHRA  (10 years ago)

ANS IS :159; (200020^12)=(5^12)(4^12)(13^12)(11^12)(7^12); Now for Digit having 7 their unit place ; we have 3 type of method :- first only combination of 7^1,7^5,7^9 and 13^3,13^7,13^11=> 6digit now; digit having 1 in unit place * digit having 7 in unit place=>45; digit having 1 in unit place *digit having 1 in unit place * digit having 7 in unit place =>108;

Is this solution Helpfull? Yes (1) | No (17)  

samarth shrivastava  (10 years ago)

ans is 3 as 20020 has one factor as 7. thus 7^n gives 7,9,3,1 in cyclic order as units place. thus 7^12 gives 7^1,7^5,7^9 positive divisors of the no.

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Raushan shukla  (10 years ago)

ans is 3 given by 7^1,7^5 n 7^9.

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Nivedita Mondal  (10 years ago)

ans is 221 .

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