what the number under the tank, or infantry, mean

[miked489]

what the number mean ,it change all the time

[Banquet]

That's basically the combat strength of the unit. It will change as the SubFormations change (reinforcements , combat losses, etc) It also changes based on the experience, moral, entrenchment and stuff like that.. so it's very rarely the same from turn to turn. That's as I understand it anyway

[Erik Rutins]

It is defined in the manual as follows:

6.11 Counter Number Formula
The numeric value on the counter of a unit is:
Counter Strength = Power Points * ( rdn / 100) + ( Power Points * ( xp / 100 )
The Power Points of all subformation types in all included release scenarios are set equal to production cost / 100.

So it's a rough form of total strength, assuming the designer has set the power points to a meaningful number (which they are in the official scenarios).