\[\boxed{\mathbf{343.}}\]
\[156 + 80 = 80 + 156 = 236\]
\[270 + 36 = 236 + 70 = 306\]
\[606 + 55 = 661 < 660 + 55 =\]
\[= 715\]
\[333 + 177 =\]
\[= 510 > 303 + 177 = 480\]
\[8 + 123 = 131 < 8 + 321 = 329\]
\[545 + 199 =\]
\[= 744 > 119 + 545 = 664\]