Is anyone good at number puzzles?

Question

In an exceptionally long corridor in a house, there are one thousand windows along one wall. Coincidentally, there are exactly one thousand people in the house. The man of the house orders the first person to open the blinds on every window. Then, he orders the second person to close the blinds on every second window. Then the third person is told to go to every third window, and close the blinds if they are open, and open the blinds if they are closed. The fourth person does this for every fourth window, and so on.

After all 1000 people complete the process, how many blinds are open?

Answer 1

I tried this for 25 windows and 25 people.

The blinds left open were 1, 4, 9, 16 and 25 (i.e. 1 squared, 2 squared, 3 squared, etc.). I assume that pattern continues leaving these open:

1, 4, 9,16, 25, 36, 49, 64, 81, 100, 121, 144, ...

The largest perfect square less than or equal to 1000 is 961 which is 31 squared so I say 31 blinds are left open.

So for any given number of windows and people, take the square root of that number and truncate anything after the decimal point. So 1,000,000 windows and people would leave 1,000 blinds open. 2,000,000 would leave 1,414.

Answer 2

2

Answer 3

a million.) 7 Wonders of the historic international 2.) 1001 Arabian Nights 3.) 12 signs and indications of the Zodiac 4.) fifty 4 playing cards in a Deck {With Jokers} 5.) 9 Planets contained in the photo voltaic gadget 6.) 88 Piano Keys 7.) 13 Stripes of the yank Flag 8.) 32 degrees Fahrenheit at which Water Freezes 9.) 18 Holes on a golf course 10.) ninety degrees in a correct perspective 11.) 2 hundred funds for Passing bypass in Monopoly! 12.) 8 sides on a end signal 13.) 3 Blind Mice (See How They Run) 14.) 4 Quarts in a Gallon 15.) 24 Hours in an afternoon 16.) a million Wheel on a Unicycle 17.) 5 Digits in a zipper Code 18.) fifty seven Heinz varieties 19.) 11 gamers on a football crew {football?} 20.) one thousand words that a photo is worth 21.) 29 Days in February in a bounce year 22.) sixty 4 Squares in a Chessboard 23.) 40 Days and Nights of the excellent Flood Days

Answer 4

one

Answer 5

this is interesting. i would assume 500, because while there is someone opening, someone else is closing, or something like that!

Answer 6

i'm just tyring to get 1000 people to come to my castle.

I'll let you know tomorrow

Answer 7

at a guess as its late and my brains not upto much tonight i say none...whats the answer?

Answer 8

one.

Answer 9

you lost me on that one

now i feel stupid!!!!

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