J. R. Wilton obtained a formula for the product of two Riemann zeta functions. This formula played a crucial role to find the approximate functional equation for the product of two Riemann zeta functions in the critical region. We find an analogous formula for the product of two Dedekind zeta functions and then use this formula to find closed form expressions for Dedekind zeta values attached to arbitrary real as well as quadratic number fields at any positive integer.