=248*[1000-303]+635*303+387*197
=248*1000-248*303+635*303+387*197
=248*1000+[635-248]*303+387*197
=248000+387*303+387*197
=248000+[303+197]*387
=248000+500*387
=500[248*2+387]
=500*883
=441500