KDA is a score that the game gives you at ranked games depending on you kills, deaths and assists.
i think, its mode of calculating is: K + A / D
like this games of mine: 5/5/34 sona games kda says 7.8:1, i ignore the :1 so its 7.8 for me (5 + 34 / 5 = 7.8) and this ryze game 2/6/0 its kda says 0.3 (2 + 0 / 6), they both are 1 game champion, now lets check another champion with more games: nunu 60/86/146, kda: 2.4 (60 + 146 / 86 = 2.395348837209302)
now, my question: what happens if there is a 0/0/0 score? or a 4/0/3 score?
PS: this wikia needs a kda page
PS2: sona is actually my higher kda and ryze is my lowest one :$