Computers encrypt digital information and allow people to collaborate across the globe. Computer science studies the theory behind mechanisms like these and the practical details needed to build them.
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What is wrong with his lyrics?
Your friend has written a program to check whether or not a number \(n\) is prime. It is very simple and works by checking if \(n\) is divisible by each number from 2 all the way to \(n1\). When you see this, you curse your friend and tell him he's wasting time.
If your friend didn't want to waste time, what is (approximately) the biggest number that he needs to check before he can determine that any number \(n\) is prime?
Suppose that on day 1, all four of the friends are sad. After a few days, the friends reach a stable emotional state that repeats itself. What is the emotional state of each person in this repeating state?
She is also worried about the security of the network. So, she needs to encrypt it.
Should she compress the data and then encrypt? Or should she encrypt the data and then compress? Or does it not matter?
Background: The tech giant Google is known to have setup such billboards in the heart of Silicon Valley, and later in Cambridge, Massachusetts; Seattle, Washington; and Austin, Texas. It read
"{first 10digit prime found in consecutive digits of e}.com".
Solving this problem and visiting the website led to an even more difficult problem to solve, which in turn led to Google Labs where the visitor was invited to submit a resume. Unfortunately, that website has been taken down.
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