Forget current table position for a second. We only have to finish above 5 teams (top 6 make the playoffs). In order to clinch a playoff spot our points have to be more than the team in 7th could possibly get. So looking at the max possible points above we already have more than PHI, ORL, or DC could get if he managed to win every game remaining for them.
That next lowest is NE who would have to win out to get 56 which is what we currently have. So our magic number to finish above NE is 1. Unfortunately finishing only above NE doesn't get us in to the playoffs. So we have to look at the next lowest max points.
Although they're currently in 3rd Columbus has played more games than anyone so their max is 60. If we can finish above them then we're in the playoffs. So our magic number is 5 to get us to 61 (I think first tie breaker is head to head so we could theoretically finish with 60 and still finish above them). Once we have 61 then it is impossible for us to finish lower than 6th.
Therefore our magic number is 5.