interesting how mathes works differently for many people. because I do 8+2 to get 10. then 7-2=5, so 10+5 = 15.

Quick mafs

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.