If 1 unit equals 10 units, and you want to scale it so 1 unit equals 1 unit, you need to multiply by 10.
To change a multiple to percent, you have to move the the decimal to the right two places, so 1 = 100%
so if you need 10 x 1, you need to multiply 10 x 100% = 1000%.
Does this help at all?