\[\boxed{\mathbf{1}\mathbf{.13}}\]
\[\textbf{а)}\ 745 + 476 = 1221\]
\[\textbf{б)}\ 472 - 398 = 74\]
\[\textbf{в)}\ 2842\ :7 = 406\]
\[\textbf{г)}\ 342 \cdot 25 = 8550\]
\[\textbf{д)}\ 47 \cdot 24 - 39 = 1089\]
\[\textbf{е)}\ 840\ :12 + 15 = 70 + 15 = 85\]
\[\textbf{ж)}\ 24 \cdot (327 - 276) = 1224\]
\[\textbf{з)}\ (247 + 578)\ :25 = 33\]