要用梯等式计算（要简便计算,x=乘号）：25x28x2 72x26+36x48 63x73-63x6325x28x2 72x26+36x48 63x73-63x63 中间是分开的

25*28*2=25*4*7*2=100*14=1400
72*26+36*48=72*26+4*9*6*8=72*26+72*24=72*(24+26)=3600
63*73-63*63=63*(73-63)=63*10=630

25*28*2
=25*2*28
=50*28
=1400
72*26+36*48
=72*26+（26+10）*48
=（72+48）*26+10*48
=120*26+480
=3120+480
=3600
63*73-63*63
=（73-63）*63
=10*63
=630

25x28x2
=25*2*28
=50*28
=1400
72x26+36x48
=36*2*26+36*48
=36*52+36*48
=36*(52+48)
=36*100
=3600
63x73-63x63
=63*(73-63)
=63*10
=630