7.2/4.5怎么简算

7.2/4.5
=（8*0.9）/(5*0.9）
=8*0.9/5/0.9
=7.2/5/0.9
=1.44/0.9
=1.6

7.2=8*0.9
4.5=5*0.9
7.2/4.5=8/5

72/45=(8*9)/(5*9)=8/5

（0。9*8）/（0。9*5）=（0。9/0。9）*（8/5）=1。6

分子分母同乘10，=72/45约掉9，=8/5=1.6
或7.2=8*0.9，4.5=5*0.9，=8/5=1.6

7.2/4.5=7.2/9 *2=0.8*2=1.6