Вычисли

1. \(4\cdot \sqrt{25}=\) [ ].
2. \(6\cdot \sqrt{81}=\) [ ].
3. \(\sqrt{36}\cdot \sqrt{16}=\) [ ].
4. \(\sqrt{49}\cdot \sqrt{64}=\) [ ].
5. \(3\cdot \sqrt{4}=\) [ ].
6. \(\sqrt{9\cdot 4}=\) [ ].