when set viable to number type in cmd
example: set /a num=0833
echo
%num%
display:
Invalid number. Numeric constants are either decimal
(17),
hexadecimal (0x11), or octal (021).
reason:
when the number has
prefix with 0, it is octal, 08 and 09 are invalid number.
when the number
has prefix with 0x, it is hexadecimal
0x12 = 18 = 22