用简便方法计算下面各题．1.8×0.9+0.185.4×0.68+3.4×2×0.4623.9-0.6×0.6-0.646.82÷4÷0.251.26÷（1.26×0.8）0.7777×0.7+0.1111×2.1．

Question

用简便方法计算下面各题．

1.8×0.9+0.18	5.4×0.68+3.4×2×0.46
23.9-0.6×0.6-0.64	6.82÷4÷0.25
1.26÷（1.26×0.8）	0.7777×0.7+0.1111×2.1．

Answer 1

（1）1.8×0.9+0.18
=1.8×0.9+1.8×0.1
=1.8×（0.9+0.1）
=1.8×1
=1.8；
（2）5.4×0.68+3.4×2×0.46
=5.4×0.68+6.8×0.46
=5.4×0.68+0.68×4.6
=（5.4+4.6）×0.68
=10×0.68
=6.8；
（3）23.9-0.6×0.6-0.64
=23.9-0.36-0.64
=23.9-（0.36+0.64）
=23.9-1
=22.9；
（4）6.82÷4÷0.25
=6.82÷（4×0.25）
=6.82÷1
=6.82；
（5）1.26÷（1.26×0.8）
=1.26÷1.26÷0.8
=1÷0.8
=1.25；
（6）0.7777×0.7+0.1111×2.1
=0.1111×7×0.7+0.1111×2.1
=0.1111×4.9+0.1111×2.1
=0.1111×（4.9+2.1）
=0.1111×7
=0.7777．