Heres the number of Archers it takes to kill without losses... yes you can bring along others but this is too have no losses..

80 Archers per 500 Supplu Troops
55 Archers per 500 Scouts
155 Archers per 500 Military Men
410 Archers per 500 Swords
340 Archers per 500 Pikemen
2000 Archers per 500 Archers

This theory has been testedand tried based upon Range over Damage versus Defense/Life. Rather simple math and thus the example below is most effective.

210 Archers to take Level 1 Barbarian Camp with no losses
840 Archers to take Level 2 Barbarian Camp with no losses
2065 Archers to take Level 3 Barbarian Camp with no losses

numbers are a lil more or less based upon testing but use your own theories and have fun

so its easy to see how you can become effective and farm faster this way by ensure rally point is leveled to allow numerous attacks at same time with barbarian camp near you. Also you may attack same camp over and over but allow to reset to full strength and resources which is 30-45 mins.

Happy hunting !