  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.
What Is the Planet Jupiter Made Of and What Gases Make Up Jupiterâs Atmosphere and Core? 2010.07.31 by Karen Hill | Updated 2014.07.11 | Filed Under: SpaceLeave a Comment. According to current speculation, Jupiter probably has a small, solid core of silica. Above that lies a shell of a different form of liquid hydrogen. Jupiterâs core is surrounded by dense metallic hydrogen, which extends outward to about 78 percent of the radius of the planet. Droplets of helium and neon precipitate downward through this layer, resulting in reduced quantities of these elements in the upper atmosphere.