Dmg = ceil(((Level*5)+Str)*(1+(Rank*0.05))*Weapon*NO)

ceil = makes it a round number
Level = your level
Str = your strenght
Rank = your rank
Weapon = depends on which weapon you are using, it uses that multiplier ( for example Q5 weapon is 2x , Q5 helicopters is 4x )
No = 10 % bonus

Хто хоче, то надрукуйте формулу в екселі, як у мене: 

=CEILING((((B15*5)+B16)*(1+(B17*0.05))*B18*B19),0.01)

           Damage    641.03
B15 - Level         21
B16 - Strenghth       154
B17 - Rank         25
B18 - Weapon      1
B19 - No             1.1

Успіхів!