To test if a number is prime, divide it by 2 and then by 3, 5, 7, and 11. If it’s not a whole number, it’s prime. Google’s name comes from “googol,” a large number. Equations were once written in words and an icosagon has 20 sides.
Prime numbers can only be divided by 1 and themselves. To test whether a number is a prime or not, it must first be divided by 2. If the number can be divided by 2 and remains an integer, it is not a prime. Once divided by 2, if the number is not a whole number, the number must be divided by 3, 5, 7 and 11. If the number is a whole number when divided by the remaining numbers listed, then it is not a prime number . If the number isn’t an integer yet, then it’s a prime number.
For example, 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29 are prime numbers according to the rules listed above. A quick fact; there are only two prime numbers that end in a 2 or a 5, namely 2 and 5.
Some interesting facts about math and numbers:
The search engine “Google” actually got its name from the spelling of a very large number, googol.
Mathematical equations were once written into words because most mathematical symbols weren’t invented until the 16th century.
Not often heard of, an icosagon is a shape with 20 sides.
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