分析:(1)根據(jù)乘法分配律進(jìn)行簡算;
(2)把320拆成40×8,然后再根據(jù)乘法交換律和結(jié)合律進(jìn)行簡算;
(3)根據(jù)乘法分配律進(jìn)行簡算;
(4)根據(jù)乘法分配律進(jìn)行簡算;
(5)先算小括號里面的加法,再算中括號里面的減法,最后算除法;
(6)先算0÷﹙
+
﹚=0,再算加法,最后算除法;
(7)先算小括號里面的加法,再算中括號里面的除法,再算加法,最后算乘法;
(8)先算小括號里面的減法,再算中括號里面的乘法,再算中括號里面的加法,最后算乘法.
解答:解:(1)
÷5+
×
,
=
×
+
×
,
=(
+
)×
,
=
×
,
=
;
(2)0.25×1.25×320,
=0.25×1.25×(40×8),
=(0.25×40)×(1.25×8),
=10×10,
=100;
(3)19.98×37-199.8×1.9+1998×0.82,
=1998×0.37-1998×0.19+1998×0.82,
=1998×(0.37-0.19+0.82),
=1998×1,
=1998;
(4)﹙
-
+
﹚×12,
=
×12-
×12+
×12,
=2-3+4,
=3;
(5)[1-﹙
+
﹚]÷
,
=[1-
]÷
,
=
÷
,
=
;
(6)[
+0÷﹙
+
﹚]×
,
=[
+0]×
,
=
×
,
=
;
(7)20-[﹙
+
﹚÷
]×1.2,
=20-[
÷
]×1.2,
=20-1×1.2,
=20-1.2,
=18.8;
(8)
×[15×﹙
-
﹚+
],
=
×[15×
+
],
=
×[
+
],
=
×
,
=
.
點(diǎn)評:四則運(yùn)算,先弄清運(yùn)算順序,然后再進(jìn)一步計算即可;能簡算的要簡算.