## Monday, August 07, 2006

### Evil numbers

In arithmetic, there are common terms such as rational numbers, irrational numbers, whole numbers, natural numbers etc. Here are some less known numbers:

1) Evil numbers: Numbers with a binary representation with even number of 1s. An example of an evil number is pi
2)Happy numbers
3) Unhappy numbers, ie numbers which are not happy.
4) Wasteful numbers: If x is a wasteful number, its prime factorisation has more digits (including the powers)than the number of digits of x. An example is 4,6,8,9,12,18 etc.
5) Frugal numbers: A non wasteful number and 1.
6) Economic numbers: Frugal numbers excluding 1.
7) I like this one the most: Lucky numbers

There are many other types of numbers. Here's a nice article on number gossip.

At 4:41 AM,  Da vidz said...

Haha lucky numbers. Not so lucky to me........ better buy 4D instead!

At 4:54 AM,  Da vidz said...

http://mathforum.org/dr.math/

Useful for teachers like us to consult on how to explain a certain concepts too.

What is the binary intepretation of pi? Can you even represent it in binary? But then the link says another definition of evil numbers.

oh i mean representation, not intepretation

At 5:18 PM,  MF, Lim said...

Where is my favourite algebraic numbers? :P

At 7:23 AM,  Anonymous said...

very nice