5.6+2.7+4.5的简便计算5.6+2.7+4.5=5.6+4.5+2.7=5.6+4.4+0.1+2.7=10+2.8=12.8
5.5+0.1+2.7+4.5=5.5+4.5+0.1+2.7=10+2.8=12.8
5.6+2.7+4.5=5+0.6+3-0.3+4+0.5=12+0.3+0.5=12.8
5.6+2.7+4.4+0.1
