about cisco 831 router interfaces

[cisco8123]

Hi, I am new and have a dummy question on a cisco 831 router.

I only see 4 fast ethernet interfaces and 1 ethernet interface on the back of the router.

however, the "show version" command shows the following:

Cisco C831 (MPC857DSL) processor (revision 0x500) with 58983K/6553K bytes of memory.
Processor board ID FOC10221TUU (2878649209), with hardware revision 0000
Chassis serial number FHK102422KM
CPU rev number 7
3 Ethernet interfaces
4 FastEthernet interfaces

Why it says 3 Ethernet interfaces?

Thanks.

[manasesramos]

How do I make it show all my ports? when I plug in something to port 1-4 it shows me on the log that I plug in to e0!