(1)12×(
+1 2
-1 3
)1 4
=12×
+12×1 2
-12×1 3
1 4
=6+4-3
=10-3
=7;
(2)4×0.8×0.25×12.5
=(4×0.25)×(0.8×12.5)
=1×10
=10;
(3)2.92×
+4.06÷23 7
1 3
=2.92×
+4.06×3 7
3 7
=(2.92+4.06)×
3 7
=6.98×
3 7
=
;1047 350
(4)85.7×25+85.7×74+85.7
=85.7×(25+74+1)
=85.7×100
=8570.