CA CS CIMA Adv Dip MA Prakash (CA CS CIMA)     21 July 2009

# Funny & Logical puzzle...

Hi Friends,

A professional college has a strange principal. On the first day, he & his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the college.

The principal asks the first student to go to every locker and open it.

Then he has the second student go to every second locker and close it.

The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it.

The fourth student does this to every fourth locker, and so on.

Then guys, the Question.....

After the process is completed with the thousand students, how many lockers are open?

Thanks,

ooops

PALNITKAR V.V. (Lawyer)     22 July 2009

bheja fry puzzle !

ritesh agarwal (Chartered Accountant)     26 July 2009

only the no.s which are perfect square will be closed

G. ARAVINTHAN (Legal Consultant / Solicitor)     26 July 2009

ritesh agarwal (Chartered Accountant)     26 July 2009

a pattern emerges when you try it out on some of the no.s

the pattern is only to be identified and i had given the pattern that the square no.s lockers are open.

the answer is too complicated for me to explain

still i try

12 no.locker will be visited by as many boys as the no of factors 12 have like1,2,3,4,6,12

all no.s except square no.s have even no. of factors so they will be  in the even state i.e closed as they were closed in the beginning.

so only square no.s are open.

actually 32 is the correct answer

I have given the no of lockers closed earlier as a hint only