解:(1)12.76-(8.9+1.76),
=12.76-8.9-1.76,
=12.76-1.76-8.9,
=11-8.9,
=2.1;
(2)1.25×43+1
×27+125%×30,
=1.25×43+1.25×27+1.25×30,
=1.25×(43+27+30),
=1.25×100,
=125;
(3)99×28,
=(100-1)×28,
=100×28-1×28,
=2800-28,
=2772;
(4)78×
,
=(79-1)×
,
=79×
-1×
,
=3-
,
=2
;
(5)(
+
)÷(
-
),
=
÷
,
=
;
(6)35×(1-
)÷
,
=35×
÷
,
=15÷
,
=27.
分析:(1)12.76減去8.9與1.76,等于分別減去8.9與1.76,再根據(jù)加法交換律進(jìn)行計算即可;
(2)根據(jù)乘法分配律進(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和減法,再計算除法;
(6)先計算小括號里面的減法,再按照從左向右的順序進(jìn)行計算即可.
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,能簡算的要簡算.