解:(1)(5.6-1.6÷2)×2.5,
=(5.6-0.8)×2.5,
=4.8×2.5,
=1.2×4×2.5,
=1.2×(4×2.5),
=1.2×10,
=12;
(2)
×9-8÷
,
=
×9-8×
,
=
×(9-8),
=
×1,
=
;
(3)2001÷
,
=2001×
,
=2001×
,
=2001×(1+
),
=2001+
,
=2001+1
,
=2002
;
(4)
+
+
+…+
,
=
+
+
+…+
,
=(
+
+
+…+
)-(
+
+
+…+
),
=(
-
+
-
+
-
+…+
-
)-
×(
-
+
-
+
-
+…+
-
),
=(
-
)-
×(
-
),
=(
-
)×(1-
),
=
×
,
=
.
分析:(1)心酸括號內(nèi)的除法,再算括號內(nèi)的減法,原式變?yōu)?.8×2.5,把4.8變?yōu)?.2×4,運(yùn)用乘法結(jié)合律簡算;
(2)把除法變?yōu)槌朔,運(yùn)用乘法分配律簡算;
(3)把除法變?yōu)槌朔,?999看作1998+1,運(yùn)用乘法分配律簡算;
(4)因?yàn)槊總(gè)分?jǐn)?shù)分母中的兩個(gè)因數(shù)相差3,于是把原式變?yōu)?img class='latex' src='http://thumb.zyjl.cn/pic5/latex/221381.png' />+
+
+…+
,再把每個(gè)分?jǐn)?shù)拆分為兩個(gè)分?jǐn)?shù),原式變成(
+
+
+…+
)-(
+
+
+…+
),然后把每個(gè)分?jǐn)?shù)拆成兩個(gè)分?jǐn)?shù)相減的形式,進(jìn)一步求出結(jié)果.
點(diǎn)評:對于簡算的題目,就要注意觀察,認(rèn)真分析數(shù)字構(gòu)成的特點(diǎn)和規(guī)律,善于靈活運(yùn)用運(yùn)算定律或運(yùn)算技巧,巧妙解答.