Why some see colours in numbers

http://news.bbc.co.uk/1/hi/health/4375977.stm

"For example, people with synaesthesia tend to want A to be red, S to be yellow and Z to be black."

I'd have to agree with them, although I'd say Z is more of a very dark blue, and A is kind of pink. And clearly 5 is green, not red...