\[\boxed{\text{260\ (260).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 2 + 96 + 98 + 904 =\]
\[= (98 + 2) + (904 + 96) =\]
\[= 100 + 1000 = 1100\]
\[2)\ 257 + 18 + 12 + 3 + 40 =\]
\[= (257 + 3) + (18 + 12) + 40 =\]
\[= 260 + 40 + 30 = 300 + 30 =\]
\[= 330\]
\[3)\ 48 + 530 + 70 + 52 =\]
\[= (530 + 70) + (48 + 52) =\]
\[= 600 + 100 = 700\]
\[4)\ 33 + 34 + 35 + 36 + 37 =\]
\[= (33 + 37) + (34 + 36) + 35 =\]
\[= 70 + 70 + 35 =\]
\[= 140 + 35 = 175\]