Spend enough time on social media and chances are you’ll see what I’ve started calling a Bad Math scam. This is where an account, looking to extract its engagement numbers, posts an equation with a challenge for people to solve. Often times he will say something like “Only 80s kids can do this” or “Brain Energy Challenge: Can you do it without a calculator?””. The only problem is that the equation is written so ambiguously that you can find multiple answers.
Here’s one I found floating around the internet a few days ago from an account that appears to be re-sharing a lot of existing content in hopes of going viral. The tweet reads (in true viral bait style) “Please don’t use a calculator, use your BRAIN: 50 + 50 – 25 x 0 + 2 + 2 =? “.
Now, the equation is ambiguous enough in its design that, depending on how you approach it, it produces a number of different answers. In this case, users concluded that the answer was definitely 0, 4, 79, or 104. The ensuing discussion often ends with a discussion of how the order of operations works and how stupid other people are. Between argument, counter-argument, and people smugly retweeting that other people didn’t pay attention to high school math, the original poster managed to get their engagement.
But there is a solution and an effective way to come up with the right answer for both this problem and all the others you see online. And I enlisted the help of a mathematician to help me explain it so that kind of viral bait would never trip you up again. Especially if you can’t remember your PEMDAS (or BODMAS, if you grew up across the pond) from high school math.
Dr Helen Crowley is a Lecturer in Mathematics at the University of East Anglia and took issue with the way I had described the equation. “The shared problem [above] is actually not ambiguous at all, “she said,” math is a very well-educated subject and there are set rules that all problems like this follow. Dr Crowley is of course referring to the Order of Operations, which explains how a multipart equation like the one above is meant to be broken down and worked out.
In the United States and United Kingdom, the order of operations is expressed under the acronyms PEMDAS (US) or BODMAS (UK). The terms may differ, but the order in which you calculate each element of the equation remains the same. You start with anything in parentheses / square brackets, then move on to anything using exponents / commands, which are numbers including square roots and powers. The above equation uses neither.
The third in the list is multiplication and division, which is the first function that we actually need to do. “For this problem, we [first] make 25 x 0 = 0, ”said Dr. Crowley. That 0 then fits into the sum, which now looks like 50 + 50 – 0 + 2 + 2. “The last two operations to consider are addition and subtraction,” Dr Crowley said, making the final sum. 50 + 50 – 0 + 2 + 2 = 104. “This is exactly what your calculator does, because it is programmed to ‘know’ the order,” said Dr. Crowley, “the above problem doesn’t is certainly not ambiguous, we just forget the rules. “
Now you may be wondering who was in charge of establishing this order, and when it could have happened. According to Dr Mark Cooker of the UEA, the current order of operations was probably first established in its present form in the mid-16th century. Prior to that, “the manuscripts were entirely verbose and free of operational symbols except for abbreviations,” said Dr Cooker. But from the middle of the 16th century, mathematics texts “were first printed in large numbers for education.”
Cooker then believes that it was the vast influence of the philosophical transactions of the Royal Society of London that “set new high standards to reduce ambiguity in the handling of powers, brackets and multiplications or additions, in the right way. order”. He said the newspaper, as it would now be described, “offers higher standards in mathematical typography as far away as St. Petersburg, where Leonard Euler worked.” Euler was one of the most pioneering mathematicians of the eighteenth century, who “published so many influential articles and textbooks”, as well as “clear explanations of the rules of BODMAS in his elementary texts must have put everyone in the spotlight. agreement on the current order of operations ”.
Now that you know how to solve those shitty equations people post on social media, don’t forget to share a link to this story to serve as a bulwark against people who are cynically trying to rekindle their engagement.
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