Question

计算．（能简算的要简算）29.07-0.9×25.5 0.8×3.2×1

计算．（能简算的要简算）29.07-0.9×25.5 0.8×3.2×1.25 4.5×0.9+5.5×0.9 20.1+19.2×0.11 3.2×9.9 10.1×8.7．

Answer 1

（1）29.07-0.9×25.5
=29.07-22.95
=6.12；

（2）0.8×3.2×1.25
=0.8×1.25×3.2
=1×3.2
=3.2；

（3）4.5×0.9+5.5×0.9
=（4.5+5.5）×0.9
=1×0.9
=0.9；

（4）20.1+19.2×0.11
=20.1+2.112
=22.212；

（5）3.2×9.9
=3.2×（10-0.1）
=3.2×10-3.2×0.1
=32-0.32
=31.68；

（6）10.1×8.7
=（10+0.1）×8.7
=10×8.7+0.1×8.7
=87+0.87
=87.87．