分析:算式(1)(5)(7)(9)(12)可根據(jù)四則混合運(yùn)算的運(yùn)算順序計(jì)算:先算乘除,再算加減,有括號(hào)的要先算括號(hào)里面的.
算式(2)(3)(6)(10)可根據(jù)乘法分配律計(jì)算;
算式(4)(11)可根據(jù)加法交換律及結(jié)合律計(jì)算;
算式(8)可根據(jù)一個(gè)數(shù)減兩個(gè)數(shù),等于用這個(gè)數(shù)減去這兩個(gè)數(shù)的和的減法性質(zhì)進(jìn)行計(jì)算.
解答:解:(1)
×22,
=
;
(2)4.6÷4+7.4×
,
=4.6×
+7.4×
,
=(4.6+7.4)×
,
=12×
,
=3;
(3)95.6×1.8+95.6×8.2,
=95.6×(1.8+8.2),
=95.6×10,
=956;
(4)3.9+4
+6.1+5
,
=(3.9+6.1)+(4
+5
),
=10+10,
=20;
(5)0.15÷0.25+(
+
)
=
+
,
=
;
(6)(
+
+
)×0.24
=
×0.24+
×0.24+
×0.24,
=0.12+0.08+0.06,
=0.26;
(7)3.5×2.7-52.2÷18,
=9.45-2.9,
=6.55;
(8)18
-5.26-4.74,
=18
-(5.26+4.74),
=18
-10,
=8
;
(9)(2
+1
)÷(6-5
),
=
÷
,
=4
;
(10)(25+
)×4
=25×4+
×4,
=100+1,
=101;
(11)
+1
+
+2
=(
+
)+(1
+2
),
=1+4,
=5;
(12)
9+3×4÷2=9
+
×
×
,
=9
+
,
=
+
,
=
.
點(diǎn)評(píng):完成本題要細(xì)心,注意小數(shù)、分?jǐn)?shù)之間的互化以及通分約分.