问题
解答题
脱式计算(能简算的简算). (
1.25×64×2.5×0.5 693×99+693
|
答案
(1)(
+1 8
-5 12
)×48,1 6
=
×48+1 8
×48-5 12
×48,1 6
=6+20-8,
=18;
(2)1.25×64×2.5×0.5,
=1.25×8×4×2×2.5×0.5,
=1.25×8×(4×2.5)×(2×0.5),
=10×10×1,
=100;
(3)693×99+693,
=(99+1)×693,
=100×693,
=69300;
(4)
÷[9 20
×(1 2
+2 5
)],4 5
=
÷[9 20
×1 2
],6 5
=
÷9 20
,3 5
=
×9 20
,5 3
=
.3 4