\[\boxed{\text{121\ (121).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\ 740 - (240 + 60) =\]
\[= 740 - 300 = 440\]
\[2)\ (840 - 40)\ :8 = 800\ :8 =\]
\[= 100\]
\[3)\ (66 - 6) \cdot 9 + 1 =\]
\[= 60 \cdot 9 + 1 = 540 + 1 = 541\]
\[4)\ (120 - 20) + 4 \cdot 5 =\]
\[= 100 + 20 = 120\]
\[5)\ 500\ :100 \cdot 5 = 5 \cdot 5 = 25\]
\[500\ :(100 \cdot 5) = 500\ :500 = 1\]
\[6)\ 300\ :10\ :10 = 30\ :10 = 3\]
\[300\ :(10\ :10) = 300\ :1 = 300\]