People are shocked that 550 /2 doesn’t equal 225
77 + 33 doesn’t equal 100
This is 2nd grade math.
77 + 33 !=100 its 110
carry the 1 after adding the first digits
550/2 != 225. check your answer by adding 225+225 its 450. 550/2=275
I’m guilty of occasional brain farts. But this is such simple math.
The existence and spread of the meme doesn’t prove that a lot of people are shocked. All you need is a small fraction of people professing they thought the wrong answer was correct and they could be lying for lols or very bad at math and primed by the presence of the wrong answer in the meme. The meme is then spread by the people shocked that anyone could be shocked.
Without a lot of work that is indistinguishable from it being spread mostly by people shocked about the correct answer.
I don’t know which is correct, but I suspect it’s the former. I base this on the popularity of commenting on and sharing slightly more complicated “math” posts on Facebook.
I hope that’s the case.
I have heard that many kids aren’t taught as much basic arithmetic. They switch to calculators and don’t reinforce the manual skills.
I was surprised a few years ago that my cousin’s daughter didn’t know the multiplication tables. She knew 2x2 4x4. But 9x8? I made a game out of it and she improved a lot. The pizza prize helped. 
I think it’s really that people are doing really, REALLY quick, back-of-the-napkin math when they see “550 / 2 <> 225”, and as a result think it looks wrong.
I mean, someone knows that 25 x 2 = 50, so something X50 / 2 should have 25 as the last two digits, right? Then when they see the “<>” sign, there’s a bit of surprise.
But on further reflection of about a second or so, it’s obvious that 5XX / 2 is at least 250, so it makes sense.
It’s kind of like the math equivalent of one of those visual puzzles - not actually hard, but confusing at first glance unless you’re someone used to thinking mathematically, which the vast majority of people are not.
I think that’s really the answer too; in their everyday lives, most people probably do some addition, subtraction, basic multiplication and division, and maybe some fractions for stuff like measuring spoons and cups, etc… And even then, it’s probably in specific quantities- i.e. whatever number divided by 100, 20, 5, and 10, or 25, 10 and 5 (in the US anyway). But taking some random quanity and dividing it by two isn’t one of those “precooked” sorts of things, so their brains aren’t primed to do it automatically like they would be, if they were counting change or something.
Nobody’s actually saying that they’re amazed that 550/2 <> 225 once they think about it. But at first glance it might seem wrong.
I see your point. If someone offhandedly said is 550/2 equal 225? I might say yes without thinking about it. Especially if I was preoccupied with other stuff.
It’s different if I’m actually doing the math myself.
The wise @bump nailed it. Folks aren’t doing the arithmetic. By and large they’re glancing at the numbers and glomming onto an answer using unconscious rule-of-thumb shortcuts.
Quick! What does this say?
Paris in the
the spring.
Here’s a more sophisticated example of a test that’s designed to elicit the difference between at-a-glance-recognition vs paying-careful-attention-thinking.
Even before Dunning-Kruger people differ widely in their skills, but suffice to say most are not that shocked. It is along the lines of Blinky and Clyde each buy something at the store. Blinky spends a dollar more than Clyde. In total they spend $1.10, so how much does each spend. Easy to get wrong in the absence of supratentorial activity.
These memes are mostly spread by people who want everyone to know that they’re too smart to fall for the tricks, just like those awful “only geniuses can get 10 out of 10 on this IQ test!” Facebook quizzes.
This classic thread is a really good example of the phenomenon at play.
I always thought that you were supposed to write it in a pyramid.
Exactly right, those aren’t really “maths questions” they are tests of perception just as your textual example is nothing to do with grammar, syntax or spelling.
Humans are great at looking for mental shortcuts and as a result we are also great at fooling ourselves.
There is a whole field of human error mitigation that is based on exactly these sort of errors and understanding why they happen and how we stop them. Those examples given above are in that sweet spot of plausible confusion where our subconscious processing misfires.
If you were forced to use the proper mathematical methods for either of those questions then the confusion would reduce and the right answers would increase. But we mostly don’t and so the errors flow. It isn’t that people are incapable of working it out, it is that they aren’t even trying to.
Now what you’ve done there is either very clumsy or very smart but also very subtle.
I sort of like it either way.
never mind…
Sorry, was too busy playing Pacman. Can I have that 1.10 for the machine please 
I can be two things.
As a great man said, it’s such a thin line… 
I always saw it in an inverted pyramid (triangle actually), with the point at the top.
I looked at these for an embarassingly long amount of time, trying to figure out why they are wrong. The most significant digits match and the other digits also match.
Look, by second grade I had already received all of my instruction in mental math.
~Max
I’m not sure that pyramid architecture is your strong point.
Nah… I’m a Cubist. 
But really. Doesn’t a pyramid normally have the “point” at the top? So if it was upside-down with the “point” at the bottom, wouldn’t that be an inverted pyramid?
Anyway, pyramids came up with the whole “Paris in the spring” thing. It was always written inside of a 2D triangle-- not 3D pyramid-- with the point down whenever I saw it.
Years and years gone by since then!
ETA: I’m not very mathy or geometrical so I could surely be screwing terms up.
I think the point was always up. You need a short word to fit in the point, and it’s easier to have short words at the start of a sentence than at the end.
I
love
Paris
in the
the spring