Saturday, October 31, 2009

157 and other numbers

I came across 157 this morning on Wikipedia.
157 is the number equal to 100 + 50 + 7, following 156 and preceding 158.
Juicy information about this number with, if you notice, links to 7, 50, 100, 156, 158.

Yup, you guessed it, just about every fairly low common integer has a page on Wikipedia. Some were created automatically - references in several other entries have created de-facto index pages. But a few have wonderful commentary a bit more interesting than 157above.

How's this:
69 is a semiprime. Furthermore, since the two factors of 69 are both Gaussian primes, 69 is a Blum integer.

Adding up the divisors of 1 through 9 gives 69.

Because 69 has an odd number of 1s in its binary representation, it is sometimes called an "odious number." Of note is that 69² (4 761) and 69³ (328 509) uses every digit from 0-9. 69 is equal to 105 octal, while 105 is equal to 69 hexadecimal. This same property can be applied to all numbers from 64 to 69.

On many handheld scientific and graphing calculators, the highest factorial that can be computed within memory limitations is 69! or 1.711224524*1098.

The number 69 can be rotated 180° and remain the same.

Oh joy. Oh bliss. TMI.