Quote Originally Posted by Оля
N. пятеро ребят
A. пятерых ребят
G. пятерых ребят
D. пятерым ребятам
I. пятерыми ребятами
P. о пятерых ребятах
The case order should be N, G, D, A, I, P.
There isn't a definite fixed order. If you don't learn the names and use the "First case, second case" nomenclature then of course it matters which order they are in, but if you name them it doesn't matter. NAGDIP is commonly used in English books on Russian.