Citizenship: What's Mathematics Have to Do With It?

My mother-in-law telephoned me early in the morning recently. She lives alone, and during the long nights, she worries. Her concern on this particular morning was whether her granddaughter (my niece) would be safe during her visit to New York City. My mother-in-law—who lives in Otley, England—had just seen the news that 49 people had been murdered by a gunman attacking a nightclub in Orlando.

I tried to use mathematics to reassure her. I explained that Orlando is 1,740 kilometres from New York, and Otley is 1,740 kilometres from Helsinki, Finland. So choosing not to go to New York because of an attack in Orlando is equivalent to friends not visiting Otley because of a threat in Finland.