1. 125x88+404x25
=125x8x11+101x4x25
=11000+10100
=21100
2.320x44+68x440
=44x(320+680)
=44x1000
=44000
3.79x79-79+22x79
=79x(79-1＋22）
=79x100=7900
4.25x57+25x42+25
=25x（57＋42＋1)
=25x100=2500