几道小学简便运算题、

0.8 X 0.25 + 0.8
=0.8*(0.25+1)
=0.8*1.25
=1
0.49 X 10.1
=0.49*(10+0.1)
=0.49*10+0.49*0.1
=4.9+0.049
=4.949
1.25 X 7.5 X 0.8 - 5.6
=(1.25*0.8)*7.5-5.6
=7.5-5.6
=1.9
5.9 X 10 - 5.9 X 3
=5.9*(10-3)
=5.9*7
=(6-0.1)*7
=42-0.7
=41.3
0.57 X 101 - 0.57
=0.57*(101-1)
=0.57*100
=57