How do you get from Penn Station to 72nd street?

It's very easy. You don't have to make any transfers. You have two options, the 1-2-3 (the red line) and the A-C-E(the blue line).

1) Take the Uptown 1-2-3 from 34th Street (Penn Station) to 96th Street. In this case, it is preferable to take the 2or 3, instead of the 1. All three of these trains (the 1, the 2 and the 3) stop at 96th Street. However, the 2 and 3 are express trains, while the 1 is local. If you take the 2 or 3, there will be only three stops: 34th Street (Penn Station) ---> 42nd Street (Times Square) ---> 72nd Street ---> 96th Street. On the 1 train, there will be eight stops.

2) You will exit the subway at 96th Street and Broadway. Walk two blocks east to 96th and Columbus: Broadway ---> Amsterdam Avenue ---> Columbus Avenue.

1) Take the Uptown C train from 34th Street (Penn Station) to 96th Street. DO NOT take the A or E trains. The A is an express train, and, unlike with the 1-2-3, 96th Street is NOT an express stop on the A-C-E. The A train will not stop at 96th Street, and the E train goes to Queens after 50th Street. So, you can only take the C.

2) You will exit the subway at 96th Street and Central Park West. Walk one block west to Columbus Avenue.

See the Related Link below for a complete New York City subway map.