55*99*25
=55×(100-1)*25
=55*100*25-55*25
=(56-1)*2500-(56-1)*25
=56*2500-2500-56*25+25
=14*4*2500-2500-14*4*25+25
=14*10000-2500-14*100+25
=140000-2500-1400+25
=136125