Ask iit jee aieee pet cbse icse state board community Discussion Response Post to: permutation n combination..!
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hemang (1665)

Blazing goIITian

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total posts: 1508    

it is pretty cool.

the door number which has been visited an odd number of times remains open in the end.

since any door is visited only the people numbered who divide the door number, it can be easily done.

only perfect squares have an odd number of factors..

find the number of perfect square below 1000.

1^1, 2^2, 3^2......., 31^2.

so 31 doors remain open in the end..


mathematics is the food of my soul. There are 3 types of people in the world. Those who can count and those who can't . :-)
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