A user requested a long equation that equals 25 for their son's birthday cake, as he will be studying physics in college. Several mathematical expressions were suggested, including the integral \int_{0}^{5}2xdx and the square root of 5^4, both of which succinctly represent the number 25. Other suggestions included using powers, such as 5^2, and more complex equations involving summations and integrals that incorporate the numbers 2 and 5, reflecting the son's age. The discussion emphasized the importance of maintaining clarity in mathematical notation, particularly with signs and terms, to ensure the equations are accurate and visually appealing for the cake.