A radical sign is a mathematical symbol used to indicate the square root or other roots of a number. It is represented by a check-like symbol (√) placed before the number or expression. For example, √4 equals 2, since 2 multiplied by itself gives 4. The radical sign can also be used for cube roots and higher roots by adding a small number before the sign, such as ∛ for cube roots. In mathematics, the radical sign is essential for simplifying expressions and solving equations involving roots. It is often used in algebra and geometry, where understanding the properties of numbers is crucial. Related concepts include square roots, cube roots, and exponents.