Washington, June 20 (IANS) A Japanese supercomputer named 'K' - capable of making 8.2 quadrillion calculations per second or equivalent to a million laptops working in tandem - has been named the most powerful system in the world, a media report said Monday.

The computer is three times faster than its Chinese rival that previously held the top position, a New York Times report said.

K, built by Fujitsu and located at the Riken Advanced Institute for Computational Science in Kobe, Japan, represents a giant leap forward in computing speed.

"It's a very impressive machine. It's a lot more powerful than the other computers," the Times report quoted Jack Dongarra, a professor of electrical engineering and computer science at the University of Tennessee at Knoxville who keeps the official rankings of computer performance, as saying.

K pushed back the previous number one, Tianhe-1A supercomputer, at the National Supercomputing Centre in Tianjin, China, to second place. Tianhe-1A was the first Chinese computer to be ranked on top.

The latest ranking of the top 500 computers released Monday, is determined by running a standard mathematical equation. The winning computer was able to make 8.2 quadrillion calculations per second, or 8.2 petaflops per second, the report said.

K is made up of 672 cabinets filled with system boards. Although considered energy-efficient, it still uses enough electricity to power nearly 10,000 homes at a cost of around $10 million annually, Dongarra said.

The fastest computer in the United States, at Oak Ridge National Laboratory was placed third.

In the top 10 list, US computers bagged five places. All of them are in government research facilities, the report said.

Supercomputers are used for earthquake simulations, climate modelling, nuclear research and weapons development and testing. Businesses also use the machines for oil exploration and rapid stock trading.