No. You roll 1d20. On 13-20, you miss. On 1-12, you hit any lower DF. So, if you roll for two attacks and the dice come up (say) 3 and 5, then the second hits DF 4 (or 3, 2, 1 or 0).
There's no addition. There's no subtraction. There's just greater, lesser and equal -- instantly and intuitively recognized by anyone to whom the sequence of counting numbers is second nature!
There's no addition. There's no subtraction. There's just greater, lesser and equal -- instantly and intuitively recognized by anyone to whom the sequence of counting numbers is second nature!