\[\boxed{\mathbf{21.}}\]
\[274 = 200 + 70 + 4\]
\[853 = 800 + 50 + 3\]
\[555 = 500 + 50 + 5\]
\[180 = 100 + 80\]
\[407 = 400 + 7\]
\[992 = 900 + 90 + 2\]
\[\boxed{\mathbf{22.}}\]
\[1)\ 138 + 27 = 165\ (учебников) -\]
\[по\ русскому\ языку.\]
\[2)\ (138 + 165)\ :3 = 303\ :3 =\]
\[= 101\ (учебник) - по\ \]
\[информатике.\]
\[3)\ 138 + 165 + 101 =\]
\[= 404\ (учебника) - привезли\ \]
\[в\ школьную\ библиотеку.\]
\[Ответ:404\ учебника.\]
\[\boxed{\mathbf{23.}}\]
\[500 - 150 = 350\ (С)\]
\[800 - 791 = 9\ (З)\]
\[360\ :6 = 60\ (Н)\]
\[470 - 469 = 1\ (Р)\]
\[96\ :32 = 3\ (А)\]
\[164 + 146 = 310\ (О)\]
\[200 \cdot 5 = 1000\ (Ь)\]
\[160 \cdot 3 = 480\ (Т)\]
\[1\] | \[3\] | \[9\] | \[60\] | \[310\] | \[350\] | \[480\] | \[1000\] |
---|---|---|---|---|---|---|---|
\[Р\] | \[А\] | \[З\] | \[Н\] | \[О\] | \[С\] | \[Т\] | \[Ь\] |