Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies. After all of the fun we’ve had recounting the tales of Knot Dude, ...
Quick: What's 19 2...without your calculator? (361.) Squaring complex, two-digit numbers in your head isn't that difficult if you know a simple trick, according to the Secrets of Mental Math author ...
A prime number is a number with exactly two factors. Prime numbers are only divisible by 1 and itself. Another way to think of prime numbers is that they are only ever found as answers in their own ...