ashecooper:
The numbers written in the "Able to" column (pertaining to literacy) reference naturalization paperwork. Even if Sarah didn't become a citizen, she must've filed a declaration of intent to become a United States citizen, also referred to as "first papers." Those numbers were written there by the INS to verify her entry into the USA. You can read more about notations made on US arrival manifests here:
http://www.jewishgen.org/InfoFiles/Manifests/-MJ