Rounding and Truncation in VB 6.0

Hi friends
,
Can anyone help me removing the left part in a number with decimal digit and rounding up of a number with decimal.

E.g consider the numbers 15.83783937 and 34.82308243 and 21.5 Now in this number I want how to code in an event that remove the part 15, 34and 21. Secondly I also want the parts 0.83783937 , 0.82308243 and 0.5 to be rounded to 4 decimal i.e 0.8378, 0.8231 and 0.5000.


Thanks and Regards-

Vijay