If everyone on Earth stood in a line so that you could say "Hi" to everybody you'd only manage to greet 1/3rd of the population before you die.

Assuming you and everyone you're greeting didn't need to sleep, eat, drink or do anything other than saying/hearing "Hi" but death from old-age still applies, but only to you. For reasons.

I don't know. I'm not showing my working out, this is showerthoughts not 'math genius' don't @ me.