In the traditional use of Roman numerals for clocks, the number four is most often written as "IV" rather than "IIII." However, there is a specific exception on clock faces where you might see "IIII" used to represent four.
The reason behind using "IIII" on clock faces is largely historical and related to aesthetics and symmetry in clock design. Here are a few points explaining this:
Aesthetic Consistency: On many older clocks, particularly those with hour numbers around the clock face, having "IIII" instead of "IV" ensures that the numbers on the clock face read in a more visually balanced manner. For example, the sequence "I, II, III, IIII, V, VI, ..." looks more symmetrical and consistent than "I, II, III, IV, V, VI, ..."
Historical Tradition: The use of "IIII" on clocks has historical roots. Early clock makers opted for "IIII" to maintain a certain visual harmony and balance, and this tradition has been carried forward in many clock designs.
Standard Roman Numerals: As mentioned earlier, in standard Roman numeral usage, "IV" is the correct way to denote the number four.
Modern Usage: In many modern clocks, especially digital ones or those with minimalistic design, you'll still see "IV" used as it's the standard and most recognized format in Roman numerals.
In summary, while "IV" is the correct representation of the number four in Roman numerals, you may encounter "IIII" on clock faces due to traditional aesthetic considerations. This usage is specific to clock design and doesn't reflect a change in the standard rules of Roman numerals.