(1) Do you know? China is the first country in the world to use the rounding method for calculation. About two thousand years ago, people have used rounding method to calculate.

(2) Among the four oceans in the world, the average depth of the Pacific Ocean is about three times that of the Atlantic Ocean, 400 meters more than that of the Atlantic Ocean, and the average depth of the Indian Ocean is less than that of the Pacific Ocean 103 meter. What is the average water depth in the Atlantic Ocean, the Pacific Ocean and the Indian Ocean?

(3) Xiaodong is a young netizen. He wants to read it online every day. Yesterday, he saw a message on the Internet: China discharges about 3 16 tons of sewage into the sea every second, which is twice that of the United States, three times that of Russia and 29 times that of other coastal countries.