After opening and closing doors with multiples of their numbers, which doors are open?

• Doors with odd number factors will be open after 100th time

• Doors with even number factors will be closed after 100...read more

after the 100th iteration, the doors that are open are those numbered 1, 4, 9, 16, 25, 36, 49, 64, 81, and 100.

after the 100th iteration, the doors that are open are those numbered 1, 4, 9, 16, 25, 36, 49, 64, 81, and 100.

the perfect squares from 1 to 100 will be opened

44.

if we divide 1-100 in 10 columns

for multiple of 2 = 5 times in 1 column so in 10 columns = 5*10=50

similarly

for multiple of 3 = 3 times in 1 column so in 10 column = 3*10 =30

for multiple of 4 =...read more

34

There are 100 doors and 100 people. The doors have two states (open/closed). All the doors are closed at first. Then the first person opens all the doors, the second person toggles the doors in multip...read more

Multiples of 100

Multiples of 100