Ответ:

  1. \(\frac18\cdot0.8\cdot10=1\).
  2. \(\sqrt{49}-\sqrt{2\sqrt{64}}-1=7-\sqrt{16}-1=7-4-1=2\).
  3. \(2\sqrt9-\sqrt{\sqrt{36}}+3=2\cdot3-\sqrt6+3=9-\sqrt6\).
  4. \(10\sqrt{0.5^2-0.3^2}=10\sqrt{0.25-0.09}=10\sqrt{0.16}=10\cdot0.4=4\).
  5. \(6\cdot\left(\sqrt{\frac56}\right)^2=6\cdot\frac56=5\).
  6. \(\sqrt{4^2+20}=\sqrt{16+20}=\sqrt{36}=6\).

Ответ: 1) 1; 2) 2; 3) \(9-\sqrt6\); 4) 4; 5) 5; 6) 6.