Elementary Brain Teaser

Fun and accessible problems for younger students or beginners. Posted every Monday, these weekly brain teasers kickstart your week with a mental warm-up.

You have a box of counting numbers from 1 to 10 (inclusive). You select one number from the box and place it back in the box.  You repeat this process by picking a number again.  What is the probability that the pair of numbers selected will sum to a prime number?  It is important to note that picking a 2 first and 3 second is a different pair from picking a 3 first and 2 second.  Remember to enter your value as a decimal between 0 and 1.


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