One position: Position 1
Position 1 covers frets 2–6 and holds eleven notes.
This position covers frets 2 to 6, and every note of the scale lies under one hand there. Six positions like it cover the whole neck, and this is the first of them.
Folded across four strings, the scale fits into a block a few frets wide, so you can reach every note without moving your hand. That block is called a position, and it is the unit you actually play in.
It is worth learning positions rather than single strings because music rarely runs up one string. Melodies jump about, and a position tells you what you can reach right now, rather than where one particular note is.
A ukulele needs fewer positions to cover its neck than a guitar does, because its neck is shorter. That makes up for having fewer places to play each note.