There are some bulbs,which are numbered from 1 to 100.all the bulbs are in on conditions. The following operations are performed:-
1. Those bulbs number which are divisible by 2 are switched OFF.
2. Those bulbs numbered which are divisible by 3 are switched ON (which are already OFF) and OFF bulbs are switched ON.
3. Similarly bulbs numbers divisible by 4 are either switched ON or OFF depending upon there previous condition
4. This procedure is adopted till 100th bulb.
At the end there were how many bulbs which were in ON condition?

• 10 bulbs which are numbered by perfect square numbers.. i.e. 1,4,9..100
• 13 years agoHelpfull: Yes(5) No(0)
• Take till 10 and off=f,on=n
  1 2 3 4 5 6 7 8 9 10
  n f n f n f n f n f FOR n=2
  ....................
  continue till n=10,in this only 1,4,9 are ON which are perfect squares.So for 100 it will be 10(ie 10 perfect squares till 100)
  
• 9 years agoHelpfull: Yes(3) No(0)
• Data inadiquate
  
• 9 years agoHelpfull: Yes(1) No(0)
• At last only that bulb remain on which have odd number of factors.
  only perfect square number have odd numbers of factors.
  so answer is 10.
• 9 years agoHelpfull: Yes(1) No(0)
• DIPIN bro can u pls tell me the soln.
  
• 9 years agoHelpfull: Yes(0) No(0)
• Please Dipin explain how you get this answer.
• 9 years agoHelpfull: Yes(0) No(0)
• dipin...can u explain this clearly??
• 9 years agoHelpfull: Yes(0) No(0)