1.计算：12.375-9.4+2.1×0.1
=2.975+0.21
=3.185
2.简算：十二又二分之一减（二分之一减十五分十一）
=12+1/2-1/2+1/15
=12又1/15
12.5×3.2×25
=12.5x8x0.4x25
=100x10
=1000