Only those deemed fit for work were tattooed, so despite the degradation, the numbers were in some cases worn with pride, particularly lower ones, which indicated having survived several brutal winters in the camp. “Everyone will treat with respect the numbers from 30,000 to 80,000,” Primo Levi wrote in his seminal memoir, “Survival in Auschwitz,” describing the tattoos as part of “the demolition of a man.”

After the war, some Auschwitz survivors rushed to remove the tattoos through surgery or hid them under long sleeves. But over the decades, others played their numbers in the lottery or used them as passwords…

“To me, it’s a scar,” said Ms. Doron, who grew interested in the numbering while drawing blood from a tattooed arm in an emergency room. “The fact that young people are choosing to get the tattoos is, in my eyes, a sign that we’re still carrying the scar of the Holocaust.”