Andrew Yang and wife Evelyn with their two sons. One of his key policies as a potential Democratic candidate is to introduce a universal basic income

As campaign slogans go, “Math!” doesn’t quite compare to “Yes we can” or “Make America great again”, but that didn’t stop about 1,500 freezing fans of Andrew Yang yelling it with abandon at a blustery rally in Washington last week.

Arithmetic was a constant theme. When a warm-up act jumped onto the stage set up in front of the Abraham Lincoln memorial, she shouted: “When I say numbers, you say . . .”

“Math!” the crowd roared, waving their “Math” signs. No doubt Lincoln, a keen student of Euclidean geometry, would have approved.

Yang, you may have gathered, is also a big fan of numbers. And he is a dark horse in the Democratic presidential primary, gathering significant and unexpected momentum — or “Yangmentum”, as