Okay I know it's 15, simple math, after all 8+8 is 16, you would have to be an idiot not to know that, so it's just 1 less than that, anyways let me pull out my calculator just to check...
this post was submitted on 01 Oct 2025
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oh i know that one from my cribbage days
Why? Just take the time to do the work properly. You will get better at it, enjoy life more.
My thought exactly. I resonate with this meme but I also try to challenge myself to do math longhand on paper
The above comment is symptomatic.
Some of us have aphantasia and can't do maths in our head.
What does not being able to see inner images have to do with math?
I'm asking because I can't see shit but I have no problems with doing math up to a certain point. Not in any way good at it but it doesn't impair my memory to the point it would be a hindrance either.
Because you can't hold two numbers in your mind simultaneously, or imagine one adding to another and the result of that. It's probably difficult to explain if you are able to visualise things.
I can do maths on paper when I can see it on front of me. But I don't have a mind's eye.
I can't see anything but I can still hold numbers (again, up to a point) in my head without any kind of problem. It's not a memory impairment in any way, at least not for me. Then again there's not that much research into it so I'm genuinely curious about your experience as well.
Yeah I can't hold the numbers in my mind. It's like i can grasp the concept of a number for a split second and then it's gone like smoke. How do you add two numbers together in your mind? Like, what happens?
Okay. That seems like an extremely inconvenient thing to live with. Must be extremely frustrating.
For me it's more like ..I can't see a 7 or an 8 but I don't have a problem with taking 2 from the 7 and "holding" the remaining 5 in my memory while I add up 8 + 2.
On the other hand if someone asks about what an apple is I can tell them they come in red or green varieties but ask me to draw one and it'll be the ugliest apple ever put on paper. Meanwhile I can draw just fine if I have a model in front of me.
The thing I seriously don't understand is why I can see my dreams though. Never made any sense to me whatsoever.
I just say I'm not good at math while i look at someone in the eyes for a little while until they do the math.
For me it's 8+8-1 since the doubles are memorized
This is the same for me, but I did 7+7+1, basically
So, for me it is 10-8=2. Then 7-2=5. And then 10+5=15.
In high school calc, I would do all kinds of algebra, integration, etc. and then at the end add 8 and 7 and get 13. All the time.
Its like when you do the whole logic and calculations part and then forget to square root the number at the end.
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Must have been doing a lot of base-12 math?
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I am an accountant, literally work all day with numbers. 8+7, fine, that's 16 minus one or 14 plus one.
8x7? Never managed to memorize the times tables so that is, well 4 7s is 14 +14, that's 28, so 8 7s is 28 + 28, which is 40 and 16 so that's 56.
I understand not everyone spends that much time with numbers when they are a kid, but having liked maths (I know, I know...), I had to add up numbers enough times to recognise the pattern. So whenever I saw ghefruifghergu8+vzeru4vgbedrzvrehb7, I knew that it will end with 5, and the preceding digit will increase by one (unless it ended with 95, but enough repetitions...).
It doesn't even take intelligence, just enough repetitions ro recognise patterns - like almost everything. The same goes for the multiplying table. 8x7 isn't 56 because of the above (rather smart!) investigation anymore, but simply because 8x7 is 56, because it was also 56 for the previous 573482967589345 times. Powers of 2, up until 20? For the first few hundred times I had to start from scratch, but after ~100 repetitions, I ended up remembering them until 64. 2^7 was easy to calculate then, it's just 64x2=128. And then it grew.
interesting how mathes works differently for many people. because I do 8+2 to get 10. then 7-2=5, so 10+5 = 15.
Neat. I just remember that 8 is 2 less than 10 and 7 is 3 less than ten, so you can either do 8-3+10 or 7-2+10. Both are 15. Its similar to how you do it but for some reason its easier for me this way.
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I don't know what to make of this comments section. This many people really don't have 8+7 down?
I don't even feel superior about it, just bewildered.
Yeah, I thought there was something more to it and am disappointed.
Maybe I just have it fresher in my head because I play a lot of Killer Sudoku. 15 pair box? That’s a 7-8 or a 6-9.
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In my case, the mental math trick suggestion (make it 10 + 5) was intended as a way to build a skill using the provided, easy example. That type of mental math can be applied to much larger numbers, particularly when combined with other mental math tricks.
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This is why learning binary is so important. In base two, the same equasion is 1000+0111=1111, now you just convert back to decimal with: 8+4+2+1= sweats and starts counting on fingers before reaching for calculator
Easy, just convert to hex, 0x0F
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Mental math tricks are important.
Take 2 from the 7 and give it to the 8. You now have 10 + 5. Much easier math.
Take 2 from the 7
Hold on, I just need to check something. Looks around nervously
Yes, that seems easier to me as well! I was not allowed to do this according to the teacher when I was a child. They wanted me to do it in some weird counterintuitive way. But I was very stubborn and I am still doing calculations in this way. She is not the boss of the way I think!
8+7 = 8 + ( 2 + 5) = ( 8 + 2 ) + 5 = 10 + 5
Then just do the column addition (1 + 0) =1 and (0+5)=5
Thus concat(1,5) = 15
Now do it where you turn all the numbers into ones via math fuckery
8+7
11+1+1+1+1
that an 11
That would require me to make a +1 and a -1 table and I would have a real hard time knowing if I made the tables display correctly.
I once typed in 1+1, though it was several term equation and I was mentally reducing each term before punching it in.
I am chronicly paranoid because I have had a low battery on an exam. I just type in simple math because it might be totally borked and you won't catch it on something complex
Wait, it gets things wrong on low battery?
It...shouldn't. The 7-segment displays will have contrast issues, then the whole thing will stop working entirely when the battery gets too low.
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Same. In contexts where there are a lot of already taxing elements, there is just no mental bandwidth for switching gears and doing the calculations. So calculator it is. I do find it important to hone my skills from time to time, just not to lose them.
When I'm doing woodworking and I need to add up some very simple measurements I always use a calculator. I could very easily do it in my head and often automatically do without even thinking about it. However I've learned the hard way it's very easy to make a simple error with even something as simple as 8+7 and chances are you won't find out till later when two parts don't fit together. That's 20 hours down the toilet, just because I didn't double check using the shop calculator.
I'm alright when it comes to mathematics, but my memory is a swiss cheese. I'll do a calculation, context switch and 3 seconds later it's either gone or I remember incorrectly. Having things written down, on paper or in a calculator, gives peace of mind.
Totally this. Find an online calc that accepts fractions and just get it done right in a few seconds vs trying to convert to 16ths or some crap. Which is why I use all metric unless I’m forced into imperial units.
None of y’all have ever played cribbage I see.
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