Vimal, a project manager, made a construction contract with another company which specifies a penalty for delay of completion beyond a certain date as follows: \(₹\)120 for the first day, \(₹\)220 for the second day, \(₹\)320 for the third day, etc., the penalty for each succeeding day being \(₹\)100 more than for the preceding day. How much money Vimal has to pay as penalty, if he has delayed the work by 31 days?
The penalty amount Vimal has to pay is \(₹\)_______