Currently available:

- 15mm T2.9
- 21mm T2.9
- 28mm T2.1
- 35mm T1.5 Super Speed
- 50mm T1.5 Super Speed
- 85mm T1.5 Super Speed
- 100mm T2.1
- 135mm T2.1

We will mix and match any way you want – with a special price just for the Super Speed lenses. 14 more words

Currently available:

- 15mm T2.9
- 21mm T2.9
- 28mm T2.1
- 35mm T1.5 Super Speed
- 50mm T1.5 Super Speed
- 85mm T1.5 Super Speed
- 100mm T2.1
- 135mm T2.1

We will mix and match any way you want – with a special price just for the Super Speed lenses. 14 more words

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.

There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97. 413 more words

It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square.

9 = 7 + 2×12… 448 more words

The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97, and 7. 557 more words

Inspired by a recent discussion on the wonders of , I started thinking about how easy it would be to generate prime numbers in . Well, unsurprisingly, it was presented as an example by Knuth using trial division in… 148 more words

Primes are a fickle group. 298 more words