Editing Items

Heya, any idea how I can edit item durability by an amount rather than %'s? /minecraft:item modify entity 0bviouslee weapon.mainhand { "function": "minecraft:set_damage", "damage": -0.1, "add": true} This command removes 10% of the durability on my item, though I'd just like to remove 1. The use case for this is quite specific to how my server works, though I'm sure there's a way! I'm a noob with this kind of command stuff haha.