The D.C. gain and steady state error for step input for  are:

Concept:

DC gain:

The DC gain is the ratio of the magnitude of the steady-state step response to the magnitude of step input.

DC Gain of a system is the gain at the steady-state which is at t tending to infinity i.e., s tending to zero.

DC gain is nothing but the error coefficients.

For type 0 system: 

For type 1 system: 

For type 2 system: 

Steady state error for different inputs is given by

Calculation:

Given:

It is a type 0 system, so:

K_p = 1 = DC Gain

Steady-state error for unit step input is given as:

e_ss = 0.5