Happy π Day!

pi.bat

@echo off
REM https://www.mathscareers.org.uk/calculating-pi
setlocal
set /A "U=1<<27"
set I=1
set /A P=3*U
set Q=0
:start
  set /A D=(I*2)*(I*2+1)*(I*2+2)
  set /A T=4*U/D
  set /A M=I%%2
  if %M%==0 (set /A P=P-T) else (set /A P=P+T)
  set /A I=%I%+1
  if %P% neq %Q% set Q=%P% & goto :start
set /A T=U
set H=.
<nul set /P=PI is approximately 
:write
  set /A D=P/U
  <nul set /P=%D%%H%&set H=
  set /A P=(P-D*U)*10
  set /A T=T/10
  if %T% gtr 0 goto :write
echo  (after %I% Nilakantha terms)