The First rig in any station will have the same number as the station.
Such as:
Engine 11
Truck 11
RA 11
The Second Rig in any station will have the same number as the station
plus 200. For the Third add 300, etc.
Such as:
Engine 229 from station 29
Engine 341 from station 41
Engine 302 from station 102
RA 241 from station 41
Reserve rigs in any station that are brought on line to cover contingencies
will have the station number plus 700, 800, or 900.
Such as:
Engine 711 from station 11
Truck 712 from station 12
Engine 825 from station 25
BLS Rescue units are in the 800/900 series. They may or may not be a second RA based at a station. Add 800 to the station number.
Such as:
RA 852 from station 52
RA 902 from station 102
You also need to remember that regardless of what number you see on the rig the dispatcher could be calling it something else.
Such as:
Engine 711 being logged on to the system as Engine 11 because of scheduled maintenance on the primary rig.