I was asked this question, and i just figured that some of those who like enigmas would try to solve this one too.
So, here it is:
you've got 100 lights related to 100 switches, numbered from 1 to 100, each light being switched off at the beginning. Then are coming, one after the other, 100 men. The first one switches all the lights.
The second one (after the 1st) switches all the lights which are a multiple of two. As a result, after him, 50 lights are on, 50s are off.
The third one (after the first two men) does the same with all the lights whose number is a multiple of 3.
And so on until the 100th man, who only switches the last light, as expected.
The question is: After the coming of the last man, how many lights are on?
So, here it is:
you've got 100 lights related to 100 switches, numbered from 1 to 100, each light being switched off at the beginning. Then are coming, one after the other, 100 men. The first one switches all the lights.
The second one (after the 1st) switches all the lights which are a multiple of two. As a result, after him, 50 lights are on, 50s are off.
The third one (after the first two men) does the same with all the lights whose number is a multiple of 3.
And so on until the 100th man, who only switches the last light, as expected.
The question is: After the coming of the last man, how many lights are on?
Mon | Tue | Wed | Thu | Fri | Sat | Sun |
1 | 2 | 3 | 4 | 5 | 6 | 7 |
8 | 9 | 10 | 11 | 12 | 13 | 14 |
15 | 16 | 17 | 18 | 19 | 20 | 21 |
22 | 23 | 24 | 25 | 26 | 27 | 28 |
29 | 30 | 31 |
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