In "25 Minutes to Go," Johnny Cash counts down the minutes to his hanging. This precipitates an argument between Robert and Jad about whether you could live without numbers. Jad introduces his newborn son, Amil, and insists that he has no concept of numbers whatsoever. Like father, like son? Producer Lulu Miller talks to Stanislas Dehaene, whose work in neuroimaging suggests that Amil probably does have a number sense. You and I might not even know what logarithmic counting is, but apparently we used it as babies. Susan Carey explains why counting pennies is no small feat. Using an experiment designed by Karen Wynn, Susan breaks down the trick that separates us from the animal world: the counting song. Producer Amanda Aronczyk's daughter Mina demonstrates how complicated this whole penny business really is.