When the SS gives them the selection, how does Eliezer pass it?

The head of Eliezer's block gives some helpful advice: run as fast as possible in front of the SS doctors, and don't be afraid. When Dr. Mengele appears, all the prisoners march in front of him as he writes down the numbers of those to be cremated. When Eliezer's turn comes, he runs as fast as he can, and his friends Yossi and Tibi tell him he was running too fast for Dr. Mengele to write his number down. Eliezer's father tells him that he also passed the selection.