Supress a duplicated value in crystal report

Question

Hi.
I m doing a crystal report.
Lets say i have a serial numbers in a column:
| Serial Number |
124000100,124000101,124000102,124000103,124000104,


I wan the values to be something like this in the crystal report view
| Serial Number |
<124000>
100,101,102,103,104

means that the same value infront is grouped,categorized under one duplicate value.

How may i do this?
Any ideas guys?