After you've finished the problem you've set youself in the OP, consider what it would take to be able to freely intermix literal numbers and quoted numbers of any (supported) base:
    123, '123', 0123, '0123', 0x123, '0x123', 0b1101, '0b1101'
(Hint: try some simple experimentation with oct; be sure to read its documentation thoroughly.)

Then also support negative and positive intermixed literal/quoted numbers:
    -123, '-123', -0123, '-0123', -0x123, '-0x123', -0b1101, '-0b1101'