Latest TCS Aptitude Question SOLUTION: The citizens of planet Oz are 7 fingered and thus have developed an umber system in base 7 . A certain street in Oz contains 100 bvuildings numbered from 1 to 100. how many 3's are

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The citizens of planet Oz are 7 fingered and thus have developed an umber system in base 7 . A certain street in Oz contains 100 bvuildings numbered from 1 to 100. how many 3's are used in numbering thers buildings?

15

14

7

21

Solution

the ans is 14. any no from 1 to 100 comes 20 times.so if base is 7 then the maximium no can be 66. the no 37,38,39,73,83,93 will not be counted.and they have six 3's. so total 3's will 20-6=14.
This answer is given by ROHIT and is correct answer

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Asked In TCS Neelkamal Sharma (13 years ago)

Solved Read Solution (4)

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Read Solution (4) :

Rohit  (13 years ago)

the ans is 14. any no from 1 to 100 comes 20 times.so if base is 7 then the maximium no can be 66. the no 37,38,39,73,83,93 will not be counted.and they have six 3's. so total 3's will 20-6=14.
and ye jo alka h iske ans mat padha karo hamesha galat hoti h.

Is this solution Helpfull? Yes (15) | No (1)  

suganya  (13 years ago)

for these type of questions,
the simple formula is (n-1)* (base)^(n-2)
n=no of digits..
in this sum, its given as 1 to 100, so for 100 the no of digits is 3
(3-1)*(7)^(3-2)= 14

Is this solution Helpfull? Yes (13) | No   

Ishan Agarwal  (13 years ago)

more clearly the number between 1 to 100 i base 7 are
1,2,3,4,5,6
10,11,12,13,14,15,16
20,21,22,23,24,25,26
30,31,32,33,34,35,36
40,41,42,43,44,45,46
50,51,52,53,54,55,56
60,61,62,63,64,65,66

now as the maximum number is 66 and 37,38,39,73,83,93 are not included
thats why answer is 20-6=14

Is this solution Helpfull? Yes (8) | No (1)  

ALKA  (13 years ago)

21

1-10---->1
11-19--->1
20-->29-->1

Is this solution Helpfull? Yes (2) | No (26)  

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