How Many Is That?

This clock is hanging on the wall of correspondent Bat's living room. What is that number between 3 and 5 (click to enbiggen)? If I know my Roman numerals (and I do) that doesn't represent any known number. Now I wonder why the manufacturer used IIII instead of the more traditional (and correct) IV. Maybe they didn't have quite enough room to squeeze it in the space they alloted, though that could have easily been adjusted. Maybe they thought that it looked more "artsy", though they did use Vs properly on the other numbers. Or just maybe they didn't know any better, which I personally think is the case. If they only had some way of researching the correct format...