| 546-398 | 457+199 | |
| 2.2×101 | 5.4×99+5.4 | 32×0.125×25 |
| | |
. |
457+199=656,
(
)×21,=
×21
,=9+5+3,
=17;
2.2×101,
=2.2×(100+1),
=2.2×100+2.2×1,
=220+2.2,
=222.2;
5.4×99+5.4,
=5.4×(99+1),
=5.4×100,
=540;
32×0.125×25,
=4×8×0.125×25,
=(4×25)×(0.125×8),
=100×1,
=100;
4.27×
+4.73÷8+
,=4.27×
+4.73×
+
,=
×(4.27+4.73+1),=
×10,=1.25;
(
×
)
,=(4.75×
)
,=4.75×(
)×
,=
×
,=
;(10.25-5.72-4.28)×
,=[10.25-(5.72+4.28)]×
,=
×
,=
;
,=12.75×

,=
×(12.75-1.75),=
×11,=1.
分析:灵活运用乘法结合率,加法运算的交换律、结合律来进行计算.
点评:此题考查了运算定律和简便计算.