117 N. 10th Street
Phone: (215) 413-2531

From the mathematics department, you have the following options to get to Penang:

Walk:Walk down Walnut street to 10th street (across the Schuylkill River and through Center City) and then head north, passing Chestnut, Martket and Arch Street. The Restaurant is in the block north of Arch street. Walking will take 30-45 minutes.
Bus:On the corner of Walnut street and 33rd street, in front of the math department, you find a bus stop of the route 42. Take this bus to 10th street (stop will be on 10th street and Chestnut). The fare is $2, exact change needed. When you get off, walk north on 10th street (see above). The buses run around 6:10, 6:15, 6:30, 6:42 etc. The bus ride should take about 20 minutes.
Warning: There is at least one other bus that stops at 33rd and Walnut. Make sure you only get on the 42.
Subway: Walk up (west!) Walnut street to 34th street and then head north to Market street. The subway station is at 34th and Market streets. You will have to buy a token (~$1.30). Take the Market-Frankford-Line eastbound to 11th and Marekt streets. Walk down Market street to 10th street and head north (see above). This line is more or less going every 10 minutes, and the ride takes about 10 minutes.

Google-Maps: Penang (A)