6's game (arithmetic a plus)

[Monk]

here is a game that will challenge your brain; using no more than 4 number 6's lets see with math how far we can go from 0-X with this; ill give a few examples... each post will be a 1-up of the previous one:
the only rules is that you can use no more than 4 6's; use your math skills for this one....

0= 6*0
1= 6/6
2= (6/6)+(6/6)
3= (6+6+6)/6

4 anyone?