If you’re of a certain age, you’ll remember that PEMDAS was a mnemonic that many of us learned in Math class that stood for doing equations in a certain order, namely parentheses, exponents, multiplication, division, addition, and then subtraction. We’ve all seen those posts on social media showing how the calculators on smartphones don’t understand the order of operations; apparently, they were absent from class on the day that PEMDAS was explained.
This is a known problem among the younger set, as my preteen already knew not to rely on smartphone calculators (he was also deeply suspicious about why he was being quizzed about math problems during summer break). I hate it when things don’t work the way they’re supposed to, so I did some experimentation.
It turns out that smartphone calculators don’t know the order of operations, but they do reliably solve equations from left to right.
So, let’s look at the Instagram post that Judie sent me yesterday, which showed this equation.
The Order of operations says parentheses first so that shortens down to 6÷2(3), which equals 1.
My Pixel calculator read this as 6÷2, then the resulting 3*(1+2), concluding the answer was 9. It’s bad math, but this is a calculator from the same company whose AI told us to put glue on pizza (cough cough, Google).
iPhone calculators aren’t any better, as you can see here.
Anyway, assuming that you need to solve this and absolutely need to use your smartphone calculator, here’s a down-and-dirty solution: put the parenthetical portion of your equation first.
Like before, the calculator reads it left to right, so it determines 2(1+2)=6 and then divides that by 6 to arrive at 1 correctly.
Math teachers everywhere should rejoice. Even with a calculator, we still need to remember what they taught us!