Tag » Eratosthenes

The Girth of the Earth: How do we know?

Recently I wrote about the circumference of the Earth, and how long it would take you to travel right round it. But how do we even know that? 774 more words


A play on primes - Part 2

In a previous post, I shared some thoughts on a couple of generation techniques for prime numbers. This post is about implementing them.

First implementation of the Sieve of Eratosthenes in JAVA. 334 more words


L4: Apennines

Impressive mountain range on the southern shores of Mare Imbrium and stretching northeast from Eratosthenes. The highest peaks reaches well over 5000 meters. 14 more words


L69: Copernicus secondary craters

So far this is one of the most fascinating objects I have observed on the moon. These chains of craterlets were formed when rubble following the Copernicus impact rained down on Mare Insularum. 63 more words


A play on primes - Part 1

So what does a geek like me do with his free time? Play around with primes. Today I wanted to share some thoughts on prime numbers, the oh so mysterious members of the number system. 328 more words


"They All Laughed at Christopher Columbus...." 1

Image from Ptolemy’s data 2

Actually, it is unlikely that anyone laughed.

Scholars had abandoned the “flat earth” idea almost two thousand years before Columbus lived.   1.112 more words


The Sieve --- elementary combinatorial applications

One powerful tool in the theory of enumeration as well as in prime number theory is the inclusion-exclusion principle (sieve of Erathosthenes). This relates the cardinality of the union of certain sets to  the cardinalities of the intersections of some of them, these latter cardinalities often being easier to handle. 506 more words

IITJEE Foundation Math IITJEE Main And Advanced Math And RMO/INMO Of (TIFR And Homibhabha)