\[\boxed{\mathbf{248.}}\]
\[1)\ 456 - 312 = 144\]
\[2)\ 254 - 112 = 142\]
\[347 - 131 = 216\]
\[567 - 322 = 245\]
\[654 - 231 = 423\]
\[466 - 215 = 251\]
\[778 - 412 = 366\]