There are 300 light bulbs lined up in a row in a long room. Each bulb has its own switch and is currently
switched off. Each bulb is numbered consecutively from
1 to 270. You first flip every switch. You then flip the
switch on every second bulb(turning off 2, 4,6...). You
then flip the switch on every third bulb (3, 6, ...). This
continues until you have gone through the process 300
times.
And how many of the light bulbs are illuminated now?