For seven decades, “never forget” has been a rallying cry of the Holocaust remembrance movement.

But a survey released Thursday, on Holocaust Remembrance Day, found that many adults lack basic knowledge of what happened — and this lack of knowledge is more pronounced among millennials, whom the survey defined as people ages 18 to 34.

Thirty-one percent of Americans, and 41 percent of millennials, believe that two million or fewer Jews were killed in the Holocaust; the actual number is around six million. Forty-one percent of Americans, and 66 percent of millennials, cannot say what Auschwitz was. And 52 percent of Americans wrongly think Hitler came to power through force.

“As we get farther away from the actual events, 70-plus years now, it becomes less forefront of what people are talking about or thinking about or discussing or learning,” said Matthew Bronfman, a board member of the Conference on Jewish Material Claims Against Germany, which commissioned the study. “If we wait another generation before you start trying to take remedial action, I think we’re really going to be behind the eight ball.”