Latest TCS Aptitude Question SOLUTION: The telephone company wants to add an area code composed of 2 letters to every phone number. In order to do so, the company chose a special sign language containing 124 different s

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The telephone company wants to add an area code composed of 2 letters to every phone number. In order to do so, the company chose a special sign language containing 124 different signs. If the company used 122 of the signs fully and two remained unused, how many additional area codes can be created if the company uses all 124 signs?

Asked In TCS litun (10 years ago)

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Read Solution (8) :

Pramod V G  (10 years ago)

122p2=14762
124p2=15252
15252-14762=490 additional codes

Is this solution Helpfull? Yes (31) | No (8)  

chaitanya  (10 years ago)

I assume that the code can consist of 2 similar sings (AA, BB)

"We know that 2 signs are unused" so now observe the conditions

1) 2 signs can be themselves as 2!=2 codes, plus 2 i.e.,(AA and BB), 4 overall.

2) With 2 unused signs we have 2 different first signs and 2 later ones ( 2*2=4).
We have another 122 signs to be the first or the second sign of the code.
Combinely we have 4*122 possibilities.

So, (122*4)+ 4 = 492.

totally 492 possible codes can be created

Is this solution Helpfull? Yes (11) | No (3)  

way  (10 years ago)

492 more signs

Is this solution Helpfull? Yes (4) | No (8)  

Ranit Bhattacharya  (9 years ago)

The phone company already created 122*122 area codes, now it can create 124*124. 124^2-122^2=(124+122)(124-122) = 246*2 = 492 additional codes.

Is this solution Helpfull? Yes (4) | No   

MD  (10 years ago)

122+122+1=245 more

Is this solution Helpfull? Yes (3) | No (7)  

DEEPAK SINGHAL  (10 years ago)

ans will be 492

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

Guru Pranav  (10 years ago)

2^124-2^122

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Bibekini Behera  (8 years ago)

124*124 - 122*122=492

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