]]]]]]]]]] set #3 to 0 so we can leave the loop > if yes increment number in cell #1 and decrease number in cell #0 by 10 [ loop while number in cell #0 is greater than 9 >- go to cell #2 and set it to minus 1 so the loop will run (i will explain that at the end of the loop) ] repeat until no number is being input (the input number can be longer than two digits) I built a code that will work with an infinite amount of input numbers but it can only output 1 or 2 digits so the range of the sum of digits can be 0-99 >, go to cell #1 and read input We want to leave the loop so go somewhere with the value '0' Substract from #1 and add to #2 now the answer is in #2 Initialize #0 with 48 (ASCII char for '0') I added quite a lot of comments so it should be relatively easy to understand.Ī brainfuck program for doing a single digit addition. My solution does single digit additions (also if the result is >9).

Numerous people have answered the question already, but since every solution differs a bit, I'll just add mine as well. I know its a bit lengthy code, may be there are better solutions possible. its weird to print 0 ahead but it is defenitely needed here we are just checking first digit is 48 or not we added a 48 before all the digits in case there is an overall carry minus 48 to get the addition correct as we add 2 ascii numbers ]>] This is a special loop to traverse LEFT through indefinite no of 0s second input is over and terminated by an = symbol first input is over and terminated by a 'plus' symbol In documentation, I used 'plus' instead of + ,as + is a valid operation in bf. My answer in this question is one solution. First you need to know how to compare two numbers. Still I prefer NOT to look into my code, as designing by yourself is easier than studying or troubleshooting a code in bf. if you want to add 57 with 3, then give input like 57+03= or 03+57=. And make sure you use the same number of digits in both inputs. Only +ve numbers can be added in my code. First I thought the name of this PL is a bit offensive but now I know, if I was authorized to name this programming language, I'd choose the same. I saw this post 2-3 days ago and I've worked on it and now I have a solution on multi-digit addition.

Brain out 2-digit number