Thomas Jiang

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A Useful Number

17 December 2020

I have always been terrible with numbers and trivia. But I have noticed that this year, I have found myself reaching back to one number in particular as a reference. 300 million or a third of a billion. That number is roughly the population of the United States.

So when I read a statistic that says that, there have been 17 million cumulative confirmed coronavirus cases in the United States, I can take a look at that number and say, this is about 5% of the United States, or 1 in 20 people in the United States. It is nice to use that as a reference point when you later read a statistic that suggests that to achieve herd immunity, roughly 40% or 50% of people would need to be immune to the virus. Or 150 million or so people. Which puts into context the number of vaccine doses that would need to be created. Currently, Pfizer will provide doses for 50 million people, or 15% of the US population, a large number but not enough to achieve herd immunity.

This number is really useful in other contexts. It’s really useful for putting into perspective things like votes. Joe Biden received 81 million votes, or a little less than 30% of the US population.

Of course, when a statistic is people, such as number of infected or number of votes, it’s use the total US population as a reference. But 300 million is also useful as a divisor. For instance, in the election context, it is estimated that the 2020 elections cost 14 billion dollars, a humongous amount of money. But if we were to divide this cost, it comes out to 42 dollars per US resident, perhaps not that extravagant a figure. Or if we wanted to take a look at the amount we spend on education, which amounts to somewhere in the ballpark of 800 billion dollars a year or a cost of 2400 dollars per US resident. Wrigley’s is estimated to sell 600 million dollars worth of gum in the US, or about 2 dollars per US resident. We can also go the other way, in case we need to put a very small number into context. If Facebook had a revenue of 40 dollars per US user, Facebook, off of the US alone, would make 12 billion dollars. And if Disguised Toast’s videos get about 3 million views, that’s about 1% of the US population, making him a minor celebrity, but not a household name.

Of course, there are limits to this single number and to truly get a grasp of a particular issue, this simply won’t do. You can of course do better, such as only taking the number of adults (as kids can’t vote) or looking at the population of your state, etc. But I have found that this number really helps me wrap my head around some very large numbers.