Length of C3:
4
9

.

Length of C4:
8
27

.

Length of C5:
16
81

.

Length of Cn:
æ
ç
è
2
3
ö
÷
ø
n-1

 

.

As n tends to infinity, this tends to 0. The Cantor set does indeed have length 0 (once you've introduced a suitable notion of ``length''!).