一、
478+147+253+22
=(478+22)+(147+253)
=700+300
=1000
二、
578-(278+155)
=578-278-155
=300-155
=145
三、
125×9×3
=125×(8+1)×3
=(125×8+125×1)×3
=(1000+125)×3
=1000×3+125×3
=3000+375
=3375
四、
386-29-171
=386-(29+71)
=386-100
=286
五、
560÷16÷5
=560÷(16×5)
=560÷80
=7
六、
25x(4x9)x6
=(25x4)x(9x6)
=100x54
=5400