When will we ever use this?

Welcome to my #Memebusters series, today’s lesson is called “When will we ever use this?” I present to you this glorious meme:

This one just made me laugh, because regardless of if this person is being serious or trolling (I honestly can never tell any more), this is such an EXTREAMLY common issue I see in arguments on the internet.

In this meme, they claim that it costs $48.00 to charge an electric car for 300 miles. Ok, let’s take that at face value for now. They go on to stat that this is $6.25 a mile, and it costs $24,000 to replace the batteries. How fast did you catch the error here? If not, don’t worry, it’s less a failure on your end, and more a failure of the educational system and how we teach math – which is, we use tips and tricks, and foster an ideology that “Math is hard” and therefore, “I can’t do it”

This issue is one that using simple dimensional analysis would catch extremely fast. 300/48 is certainly 6.25, that itself is not the problem. The problem comes in the unit tracking. If we do 300/48, we are saying 300 Miles / 48 Dollars. That gives us an answer of Miles per dollar. That means it is 6.25 miles for ever dollar or every dollar we spend would get us 6.25 miles.

If you want the answer in how many dollars each mile costs, you need to flip it. 48 Dollars / 300 Miles. Which gives us $0.16. It costs 16 cents for every mile we drive given these numbers. Remember that the division sign “/” can be read as “per” 48 dollars per 300 miles equals 0.16 dollars per mile.

That being said, this sort of argument is also completely useless, because the answer is so incredibly relative to where you are, and how much the cost of power is where you charge. That price can differ greatly not only based on what country or state you are in, but if you are home charging or using a charging station someone else.