Many do, but not all clock towers use roman numerals.
In Roman Numerals, 4 is represented as IV. Many, but not all, clock faces use IIII for 4. It is thought that this is because it provides a better visual balance to VIII for 8 on the other side of the clock face.
Letters are not numbers. Not all letters in the alphabet represent Roman numerals though some letters do.
As all United States issued paper currency contains Roman numerals, and such currency is traded worldwide, it is safe to say that nearly all countries use Roman numerals. However, there are no countries or cultures alive today which use Roman numerals for counting or math on a day-to-day basis.
You'll see a lot of Roman Numerals in Chemistry. When naming compounds, you'll need to know the difference between Iron (IV) Carbonate and Iron (II) Carbonate, for example. In plays, often acts and scenes are organized with Roman Numerals. (Act III, Scene I). And, in all honesty, lots of people will use Roman Numerals just to make something look fancier. Its typically a good idea to know at least the first five roman numerals off the top of your head.
Xviii.x.lxxxxi. All in capital letters.
Necessity is the mother of all inventions and Roman numerals were needed in the past just for the same reasons that we still need numbers today.
All numbers can be written in roman numerals. 2786 is written as MMDCCLXXXVI.
1311 is already in numerals but if you mean as in Roman numerals then they are MCCCXI
Romans used Roman numerals as their form of numbers. Romans needed Roman Numerals because they needed numbers to count, tell time, and do other things in life that involved numbers. Roman numerals were used because they could all be scribed using a flat chisel i.e X I V M.
Letters C I V I L are all Roman numerals = 100 1 5 1 50
mccxciii (in all capital letters)
Modern Romans use Roman numerals about as infrequently as the rest of the western world. Arabic numerals was much easier to use for all purposes, so the old Roman numerals are used only in formal notices like foundation stones, and often, not even then. In ancient times, before Arabic numerals were introduced to Europe, the ancient Romans used Roman numerals for all activities that required counting or arithmetic. That included commercial transactions, accounting (such as it was), calendars, etc.