Some Roman Numerals are:
I, II, III, IV (or as some clockmakers say it, IIII), V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII, XVIII, XXI, XX, XXI, XXII, XXIII, XXIV, XXV, XXVI, XXVII, XXVIII, XXIX, XXX.
Those Roman Numerals represent the numbers 1-30. Hope that helps.