3.75×9.8+3.75×0.2=3.75×（9.8+0.2）=3.75×10=37.5
2.6×（2.3+4.35÷2.5）=2.6×（2.3+1.7）=2.6×4=10.4
999.999÷666.666=999999÷666666=1.5
后两个用简便方法还不如直接算来得快呢