Adding up all the windows in Manhattan

 A typical question for M.B.A. students when interviewing for their first internship or job is: “How many windows are there in all the buildings in Manhattan?” And while the question is obviously meant to test an applicant’s critical thinking skills rather than their knowledge of a precise answer, a rough estimate might be achieved merely for the sake of curiosity.

First of all, there can be no precise figure for the number of windows in Manhattan, simply because there are no uniform buildings in Manhattan. But according to the New York Times, one can estimate that there are approximately 47,000 buildings of all kinds in Manhattan, depending on the source. However, even knowing this fact may not help, since the rest would be pure guesswork.

Another boss-impressing approach might be to estimate the rough number of square blocks in Manhattan — roughly 200 by 10. Next, subtract 150 square blocks for Central Park, which leaves 1,850. Then estimate the average number of windows on one floor per street block and the average windows per floor per avenue block – the Times suggest about 25 (times 2), and 75 (times 2), respectively. This rounds off to about 200 windows per block floor.

However, the next problem is coming up with an average building height – something that the City Planning Department doesn’t track. Again, the Times guesses an average of 10 stories, making 2,000 windows per square block. Add another 500 hundred or so for small inward facing windows, and multiply those 2,500 windows by 1,850 blocks: 4.6 million windows total.

And unfortunately that guess may be as close as any obsessive urbanite can get. [NYT] –Christopher Cameron