Prime numbers are whole numbers greater than 1 that are not divisible by any whole number other than 1 and itself. The first few are 2, 3, 5, 7, 11, 13 … To explain how the RSA algorithm works ...

Numbers like 2, 3, 5, 7, and 11 are all prime numbers. What fewer people know is why these numbers are so important, and how the mathematical logic behind them has resulted in vital applications ...

If you do this with all numbers from 2 to 100, only prime numbers will remain. Sieving multiples of 2, 3, 5 and 7 leaves only the primes between 1 and 100. Courtesy of M.H. Weissman ...

Here’s the idea of the sieve. First, filter out multiples of 2, then 3, then 5, then 7—the first four primes. If you do this with all numbers from 2 to 100, only prime numbers will remain.

“A prime number is that which is measured by the unit alone,” mathematician Euclid wrote in 300 B.C. This means that prime numbers can’t be evenly divided by any smaller number except 1.

We have known for millennia that an infinite number of prime numbers, i.e., 2, 3, 5, 7, 11, etc., can be divided by themselves and the number 1 only.

The Great Internet Mersenne Prime Search, an organization devoted to doing exactly what its name suggests, announced that it had discovered a new prime number, the largest ever found: 277,232,917 ...

The largest known prime number has been discovered by an amateur researcher and former Nvidia employee. The new number is 2 136,279,841 – 1, which beats the previous title holder (2 82,589,933 ...

If you do this with all numbers from 2 to 100, only prime numbers will remain. Sieving multiples of 2, 3, 5 and 7 leaves only the primes between 1 and 100. Courtesy of M.H. Weissman.