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Which two keys can’t open any doors?

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Which two keys can’t open any doors?
posted May 13, 2014 by Swati Arora

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2 Answers

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Monkey & Donkey can't open the doors

answer May 13, 2014 by Kunal Shah
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Lucky and risky cant open any door.

answer Jun 19, 2014 by Binu Mon

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Whilst my body is usually made from wood,
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There are 100 doors in a row, all doors are initially closed. A person walks through all doors multiple times and toggle (if open then close, if close then open) them in following way:

In first walk, the person toggles every door.

In second walk, the person toggles every second door, i.e., 2nd, 4th, 6th, 8th, …

In third walk, the person toggles every third door, i.e. 3rd, 6th, 9th, …


In 100th walk, the person toggles 100th door.

Which doors are open in the end?

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