Answer based on context:

The Survey received sufficient information to detail every ship used by the Japanese during the war. They noted that the Imperial Japanese Navy began the war with 381 warships of approximately 1,271,000 tons, and completed another 816 ships of 1,048,000 tons during the war. Of these, 1,744,000 tons were sunk; "625,000 tons were sunk by Navy and Marine aircraft, 375,000 tons by submarines, 183,000 tons by surface vessels, 55,000 tons by Army aircraft, and 65,000 tons by various agents".

How many more tons were sank by the best method compared to the worst?
570000