Here (below) is a BTM to answer a math question from the folklore (question at the end). It doesn't work because I can't get past the marked like. Whenever I reach it (first time when count == 1601) I get Code: TCC: V:\number.btm  Syntax error "10*n+g" At that time, BDEBUGGER tells me n = 123252 and g = 1 (which are OK). News flash! ... It works if, in that line only, I use "%n" instead of "n" (and it arrives at the right answer). I don't get it. This must be a very obscure bug (or I'm missing something utterly obvious). Code: set count=0 do a=1 to 9 by 2 do b=2 to 8 by 2 do c=1 to 9 by 2 do d=2 to 8 by 2 do f=2 to 8 by 2 do g=1 to 9 by 2 do h=2 to 8 by 2 do i=1 to 9 by 2 set /a count+=1 set bcontinue=0 set /a n=100*a+10*b+c if %@eval[n MOD 3] NE 0 iterate set /a n=10*n+d if %@eval[n MOD 4] NE 0 iterate set /a n=100*n+50+f if %@eval[n MOD 6] NE 0 iterate set /a n=10*n+g & REM <===================== this line if %@eval[n MOD 7] NE 0 iterate set /a n=10*n+h if %@eval[n MOD 8] NE 0 iterate set /a n=10*n+i if %@eval[n MOD 9] NE 0 iterate do z=1 to 9 if %@index[%n,%z] == -1 (set bcontinue=1 & leave) enddo if %bcontinue == 1 iterate echo %n enddo enddo enddo enddo enddo enddo enddo enddo The question: Find a 9-digit number which uses each of 1, 2, ..., 9 exactly once, and has the property that, for i=1 to 9, the number comprising its left-hand i digits is divisible by i. The answer is unique.