Clock-faces with Roman numerals usually represent 4 by IIII rather than IV. This, as stated above, is generally taken to be so that the four elements of the number better balances the four elements of VIII for 8 on the same level at the other side. However, the clock-faces on the �Big Ben' tower at the Palace of Westminster - probably the best-known such clock-face in the entire world - actually uses IV for 4! Click
here for a close-up picture of it. It shows clearly - though almost upside-down - that the 4 is IV and not IIII.
In Roman times either form was used, but legend has it that the IIII tradition for clocks began when a French clockmaker made a timepiece for the king. The latter decided that IV was wrong and - when the clockmaker insisted it was right - he was reminded that the king was never - ever - wrong! So the IIII version was preferred thereafter. Believe that or not, as you please!