The Roman numerals V, X, L, C, D, M originated in various ways[2].
V represented originally the open palm with the thumb extended, just as our 0 (zero) is thought to represent a closed hand.
X perhaps =
, an old form of θ;; according to others, it is merely two V's placed together.
L =
=
or χ, a Greek letter which the Romans did not need in their alphabet and hence used only as a numeral.