分析:(1)先算小括号内的,再算中括号内的,最后算除法;
(2)把分子中的3.4看,作3.5-0.1,括号内运用乘法分配律简算,发现括号内的数与分母相同,约分即可;
(3)此题数字很有规律,根据其特点,把原式变为
1.2×1.2×1.2×27+8×27+×27 |
1.2×1.2×1.2×8+8×8+×8 |
,分子与分母部分运用乘法分配律计算.
解答:解:(1)[1-(3.1-3.09)]÷(0.8+
),
=[1-0.01]÷(
+
),
=0.99÷
,
=
×
,
=
;
(2)
2005×(3.4×69+3.5) |
3.5×69-3.4 |
,
=
2005×[(3.5-0.1)×69+3.5] |
3.5×69-3.4 |
,
=
2005×[3.5×69-6.9+3.5] |
3.5×69-3.5 |
,
=
2005×[3.5×69-3.4] |
3.5×69-3.4 |
,
=2005;
(3)
1.2×3.6×10.8+2×6×8+×× |
1.2×2.4×4.8+2×4×8+×× |
,
=
1.2×1.2×1.2×27+8×27+×27 |
1.2×1.2×1.2×8+8×8+×8 |
,
=
(1.2×1.2×1.2+8+)×27 |
(1.2×1.2×1.2+8+)×8 |
,
=
.
点评:此题考查的目的是对四则混合运算顺序的掌握,以及采用运算技巧灵活简算的能力.