  Since 990 is divisible by ten, the answer is 990. If you were rounding off 994 the answer would also be 990. If you were rounding off 995, the answer would be 1,000.
Jupiter is the largest and most massive planet in the solar system. It was named after the chief Roman god. It is a gas giant composed of liquid and gaseous matter, and has many moons. Some of the storms in its atmosphere have lasted hundreds of years.
Above the liquid lies 600 miles (960 km) of mostly hydrogen and helium gas, with some methane, ammonia, neon, oxygen, phosphine, and other gases. The size of Jupiter ensures enough gravity to keep the gases in orbit.