I’ll be honest— math was never my strong point. I was too much of a dreamy, creative, English-class kid to find much joy in numbers. Luckily, that all changed when I discovered statistics. Now I find the intricacy of numbers to be fascinating— and if this viral math problem is any indication, many others do too!
Recently, this little diddy of a math problem has been taking the internet by storm.
Originally posted in 2016, the problem is currently making its rounds again— and while it seems easy on the surface, it’s creating some epic debates. Apparently, quite a few people have been doing this problem wrong thanks to an older method taught in schools.
To solve the problem, one must use the order of operations.
Most of us learned the order of operations using an acronym of the steps (PEDMAS/PEMDAS, BODMAS/BOMDAS) or through the popular mnemonic ‘Please Excuse My Dear Aunt Sally’, which tells us parentheses need to be calculated first, followed by exponents, then multiplication and division, and finally addition and subtraction.
Most people agree, then, that the parentheses must be calculated first:
This gives us:
But the next step is where people start to differ… According to modern scientific calculators, the parentheses imply an implicit multiplication, meaning:
Because multiplication and division hold equal value in the order of operations, we’d simply calculate from left to right:
Finally, we’re left with our answer:
So, why are so many people claiming the answer is 1?
According to the MindYourDecisions, a YouTube channel dedicated to math, the answer 1 can be argued from a historical perspective. Apparently, prior to 1917, the order of operations had a different understanding than what we use today.
Using the historical method, we’d still calculate the parentheses first. However, things change in the second step.
Historical textbooks had a special rule. This rule stated that when a division symbol was used, one should divide the entire product of the left by the entire product of the right.
Using this method, you would calculate the right side product first, giving us:
MindYourDecisions believes this special rule is the result of historical typesettings. It’s easier to simply write the division symbol and have the reader know you want to divide everything on the left with everything on the right than to use a fraction format (which would take up a lot of space) or to keep adding parentheses everywhere.
So, while the correct answer is 9— there is a historical argument to justify the answer 1.
Since being uploaded, MindYourDecisions’ video has been viewed 11 million times.
“Moral of the story: the division symbol is awful, and you shouldn’t use it.”