\[\boxed{\mathbf{Вариант\ 1.}}\]
\[\boxed{\mathbf{1.}}\]
\[840 + 1 = 841\]
\[Ответ:\ 841.\]
\[\boxed{\mathbf{2.}}\]
\[7\ сот.\ 6\ дес. = 760\]
\[Ответ:\ 760.\]
\[\boxed{\mathbf{3.}}\]
\[630 - 400 = 230\]
\[Ответ:на\ 230.\]
\[\boxed{\mathbf{4.}}\]
\[260 + 60 = 320\]
\[Ответ:320.\]
\[\boxed{\mathbf{5.}}\]
\[890 - 70 = 820\]
\[Ответ:820.\]
\[\boxed{\mathbf{6.}}\]
\[409 = 400 + 9 = 4\ сот.\ + 9\ дес.\]
\[\boxed{\mathbf{7.}}\]
\[369\]
\[6 - единиц\ десятков.\]
\[\boxed{\mathbf{8.}}\]
\[\boxed{\mathbf{9.}}\]
\[790 - 560 = 230\]
\[840 - 230 = 610\]
\[Ответ:610.\]