If you could say hello to a new person every second without taking a break and working around the clock, how many people could you greet in a day? How many in a year? How long would it take you to...

If you could say hello to a new person every second without taking a break and working around the clock, how many people could you greet in a day? How many in a year? How long would it take you to greet the 88 million people who were added to the world’s population in 2015? At this same rate, how many years would it take you to greet all 7.3 billion people on the planet?