January 27 marks 75 years since the liberation of Auschwitz-Birkenau, the largest Nazi extermination camp. But even as some 40 heads of state gathered in Jerusalem this week to commemorate the six million Jews who were killed, a recent Pew survey revealed that many American adults don't know basic facts about the ethnic cleansing of Europe's Jews during the Second World War. Fewer than half of those polled knew how many Jews were killed in the Holocaust, and close to a third didn't know when it actually happened. Here's a look at some of the numbers.
