CXXVI is the Roman numeral representation for the number 126. Roman numerals are a numeral system originating from ancient Rome, using combinations of letters from the Latin alphabet. In this system, "C" stands for 100, "X" for 10, and "VI" for 6, which together add up to 126. The number 126 can be found in various contexts, such as mathematics, history, and even in popular culture. For example, it is the atomic number of nobelium, a synthetic element, and can also represent significant dates or events in history, like the year 126 AD.