where does 0x come from? [duplicate]

Question

Possible Duplicate:
Why are Hexadecimal Prefixed as 0x?

I just saw a comment a friend of mine made:

3x12=36
2x12=24
1x12=12
0x12=18

Which made me wonder..
Why did they choose 0x as prefix for hexadecimal numbers? Is there any history behind this decision?

Answer 1

I think, because x comes from hex and 0 is to indicate that it is a number.