Press ups aren't really a test of chest strength, they're more of a test of muscular endurance. strength is when you lift MORE, endurance is when you do the same weight but more reps.
If you want to be able to do lots of pressups, heres what i did and i got up to doing 63 in 1 set.
Do as many as you can till you physically can't do another, rest 60 seconds, do as many as you can, rest 60 seconds, repeat. Do that untill you reach 100 press ups, do that once a day and when that becomes too easy (you can reach 100 press ups in roughly 2-3 sets) then up the number to 150, then 200 and so on