第一种 (300+6)x12 25x(4+8) =300x12+6x12 =25x4+25x8 =3600+72 =100+200 =3672 =300 第二种 84x101 504x25 =84x(100+1) =(500+4)x25 =84x100+84x1 =500x25+25x4 =8400+84 =12500+100 =8484 =12600 第三种 99x64 99x16 =(100-1)x64 =(100-1)x16 =100x64-64x1 =16x100-16x1 =6400-64 =1600-16 =6336 =1584