0 written abbreviation for billion
1 written abbreviation for born :
2 the second letter of the English alphabet
3 in Western music, the seventh note in the scale (= series of notes) that begins on the note C, or a set of notes based on this note
4 a mark that means very good, given to something of satisfactory quality, esp. school work:
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.