\[\boxed{\mathbf{81.}}\]
\[1)\ 920,\ 820,\ 720,\ 620,\ 520,\ 420,\ \]
\[320,\ 220,\ 120.\]
\[2)\ 960,\ 860,\ 760,\ 660,\ 560,\ 460,\ \]
\[360,\ 260,\ 160.\]