The result or effect of changing the Roman numeral IV?

Answer 1

At one time the Roman numeral IIII represented the number 4 but in an effort to make it conform with the rules of writing Roman numerals, which state that no numeral should appear more than three times in succession, IIII was dropped in favour of IV. This means that it conformed with the gerneral pattern, after all XL = 40 (XXXX is never used) and CD = 400 (CCCC is never used).

Answer 2

Changing the Roman numeral IV to a different representation would simply alter its symbol, but not its value. In Roman numerals, IV represents the value 4. Changing it may involve using an alternative form like IIII or a different numerical system altogether, but the numerical value will remain the same.