Damage calculation in battle.

What is planned requires more than a month of work, considering real-life commitments. And right away, I would like to clarify one point with the experts: when calculating the damage dealt, the program calculates everything smoothly, but an unclear situation arises with the calculation of damage from some level 1 troops to level 7 troops. Example. For a hero without an attack skill, with an attack of 0, on neutral ground: 010 halberdiers deal 07-011 damage to an archangel, while the formulas show 08-012; 100 halberdiers deal 79-119 damage to an archangel, while the formulas show 80-120. For any number of troops, one unit of damage is lost. And this is the case for attacks from many (but not all) level 1 troops on some level 7 troops. If anyone knows, please explain what the catch is.