Applications
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* finding prime numbers
* file management
* adjusting phone and email formats with regular expressions
* find words in sentences with regular expressions
* demonstrate Zipf's law
* json data and NOAA API
* CodeWars
* web scraping
* speech recognition
* selenium
* A simple flask app


Problem
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Suppose you throw random darts at a unit square in the first quadrant:   0 <= x <= 1  and 0 <= y <= 1.   What is the probability that a dart will land in this section: 0 <= x <= 0.25 and 0 <= y <= 0.25?  Now compute the probability that the dart will land inside the unit circle x^2 + y^2 ≤ 1 still keeping both x and y between 0 and 1?   How can we use this probability?