CrLf

算是很容易，不过超过上限怎么办

@echo off&setlocal enabledelayedexpansion
set /a l=3*12
set tmp=0 1
for /l %%a in (-%l%) do ( 
   for /f "tokens=1,2" %%b in ("!tmp!") do set /a tmp=%%a+%%b
   set tmp=%%b !tmp!
)
echo %tmp%
pause
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前头绕弯了，这样更好：

@echo off&setlocal enabledelayedexpansion
set /a l=3*12,a=0,b=1
for /l %%a in (-%l%) do (
   set /a "b=a+(a=!b!)"
)
echo %b%
pause
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CrLf

已修改
大数计算用纯批来做很勉强，虽然加法是其中最简单的...

CrLf

大数应该都是这样算的吧：

@echo off&setlocal enabledelayedexpansion
set a=1023423423324
set b=1231232
for %%a in ("a1=!a:~-9!" "a2=!a:~0,-9!" "b1=!b:~-9!" "b2=!b:~0,-9!") do (
   for /f "tokens=1* delims==0" %%b in (%%a) do set /a "%%b=%%c-0" 
)
set /a "n=a1+b1","m=a2+b2+m%%1000000000"
echo %a1%  %a2%  %b1%  %b2%  %m%  %n%
for /f "tokens=* delims=0" %%a in ("0!m!!n!") do echo %a%+%b%=%%a
pause
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笔算的办法...