Prime Numbers & The Sieve of Eratosthenes
Brett Berry

many many many years ago, I took a math aptitude test and one of the problems had to do with square numbers…(50 years has blurred my memory as to the original problem, but the crux was that only a few numbers are possibly square…since any two numbers that end in zero, when multiplied together will end in 0, ONE 1x1 will end in 1 when multiplied together…2x2 ends in 4, 3x3 in 9, and 4 x4 in 6, 5x5 in 5, 6x6 in 6, 7x7 in 9, 8x8 in 4, 9x9 in 1…so if a number doesn’t end in 0,1,4,5, 6, or 9, it is not a perfect square. so 40% of all numbers are eliminated on inspection of the last digit.

One clap, two clap, three clap, forty?

By clapping more or less, you can signal to us which stories really stand out.