83249+6710*80=620049 (6710*80=536800, 83249+536800=620049)    

 264037+516600:900-17080=229818 (516600/900=861, 264037+861=246898, 246898-17080=229818)

450430-196000:700+98764= 548914 (196000/700=280, 450430-280=450150, 450150+98764=548914)