1) The ocean covers about 71% of the Earth's surface and contains roughly 97% of the planet's water.

2) The rapid development and adoption of cryptocurrencies, such as Bitcoin and Ethereum, have sparked discussions on the future of finance, decentralization, and the potential of blockchain technology to disrupt traditional financial systems.

3) The national animal of Australia is the kangaroo.

4) The name "Bluetooth" comes from the 10th-century Danish king, Harald Bluetooth, who united Denmark and Norway.