There are several reasons this might have been the case, all related to marketing. The Pentium 4 was released at a time when AMD was just beginning to become a major competitor, and the Pentium III was having trouble keeping up. Calling the successor "Pentium IV" may have drawn jokes that the processor was in some sort of trouble or needed help, as "IV" in English is used as an abbreviation for "intravenous," and is used in medicine as a way of transfusing blood or replenishing lost fluids and nutrients. Similar jokes were made later on about the Pentium 4 EE, calling it the "Emergency Edition."
Another reason is that "IV" implies that there will be a sequel, forcing Intel to use the Pentium brand for another iteration.
Arabic numerals are called that because the European interpretation of those numbers comes from the Arabs. The numerals are called Arabic numerals (even though they do not resemble modern Arabic numerals in the slightest) to distinguish them from Roman numerals.
30 in Arabic numerals is ٣٠
In Arabic numerals, it is 616. In Roman numerals, it is DCXVI.
The Roman numerals lvi or LVI converted into Arabic numerals are 56
The Roman numerals LXVII=67 in Hindu Arabic numerals.
192 is already in Arabic numerals
44 IS Arabic Numerals.
The Roman numerals of XXVIII are the equivalent of 28 in Hindu-Arabic numerals
dcccxiii in Roman numerals is equivalent to 813 in Hindu-Arabic numerals.
Hindu Arabic numerals are the ones we use. 39 is already in Hindu-Arabic numerals.
The equivalent Arabic numerals of the Roman numerals CC are 200
The Roman numerals of XX are the equivalent of 20 in Hindu-Arabic numerals