gistfile1.txt

NumericLiteral ::
  DecimalLiteral
  HexIntegerLiteral
  OctalIntegerLiteral

DecimalLiteral ::
  DecimalIntegerLiteral . DecimalDigits(opt) ExponentPart(opt)
  ...

DecimalIntegerLiteral ::
  0 
  NonZeroDigit DecimalDigits(opt)

...

OctalIntegerLiteral ::
  0 OctalDigit
  OctalIntegerLiteral OctalDigit

...

Let's start parsing! ^ indicates which character we're on
010
^

Hey, that's a number. Time to pass it to NumericLiteral.
NumericLiteral
  DecimalLiteral
    DecimalIntegerLiteral
      0 [end]

010
 ^

Hang on...in DecimalIntegerLiteral, it says we can't have anything after a 0!

Fail. Guess we're not a DecimalIntegerLiteral, and nothing else matches in
DecimalLiteral. Let's try again.

010
^

NumericLiteral
  HexIntegerLiteral
    0 x HexDigit

Well, our 0 matches, but it's not followed by any x. Another fail. Let's try
again.

NumericLiteral
  OctalIntegerLiteral
    0 OctalDigit

Whadya know, our 0 matches.
(MV = 0)

010
 ^
(MV = 0*8 + 1 = 1)
And 1 is an OctalDigit, matches as well!

010
  ^
(MV = 1*8 + 0 = 8)
And so is that last 0! Huzzah!

MV = 8