Ответ:

  1. \(0.2^9\cdot5^9=(0.2\cdot5)^9=1\).
  2. \(4^3\cdot25^3=(4\cdot25)^3=100^3=1\,000\,000\).
  3. \(\left(\frac14\right)^8\cdot8^8=\left(\frac84\right)^8=2^8=256\).
  4. \(0.8^4\cdot125^4=(0.8\cdot125)^4=100^4=100\,000\,000\).
  5. \(\left(2\frac13\right)^7\cdot\left(\frac37\right)^8=\left(\frac73\right)^7\cdot\left(\frac37\right)^8=\frac37\).
  6. \(0.5^{17}\cdot2^{19}=\left(\frac12\right)^{17}\cdot2^{19}=2^2=4\).