Subscript Four

Subscript Four at U+2084 is a small lowered digit used to write the number 4 below the normal text line. It belongs to the Superscripts and Subscripts block and functions as a ready-made subscript character when mathematical or technical notation needs a plain-text form. Its most common use is in chemistry and scientific text, where it helps indicate counts in formulas when full equation formatting is not available. For example, C₄H₁₀ represents butane, and SO₄ can denote the sulfate group when used in chemical notation. It also appears in physics, engineering, and mathematics for indexed variables or sequence terms, such as x₄ for the fourth component or a₄ for a coefficient. Subscript digits are useful in filenames, database labels, chat, plain-text notes, and educational materials where rich text subscripting may be inconvenient. The main practical caution is that this is a distinct Unicode character, not simply a styled version of the ordinary digit 4, so searching or sorting may treat ₄ differently from 4.