7.5*23+31*2.5简便运算 0.79*0.46+7.9*0.24+11.4*0.079的简便运算
问题描述：
7.5*23+31*2.5简便运算 0.79*0.46+7.9*0.24+11.4*0.079的简便运算
答
甲、乙两数的差是7.02，甲数的小数点向右移动一位就等于乙数。甲、乙两数分别是多少？？？
答
（1）
7.5*23+31*2.5
=7.5*23+23*2.5+8*2.5
=23*（7.5+2.5）+20
=230+20
=250
（2）0.79*0.46+7.9*0.24+11.4*0.079
=0.79*（0.46+2.4+1.14）
=0.79*4
=3.16
答
7.5*23+31*2.5=2.5*3*23+31*2.5=2.5*69+31*2.5=2.5*(69+31)=2.5*100=2500.79*0.46+7.9*0.24+11.4*0.079=0.79*0.46+0.79*2.4+0.79*1.14=0.79*(0.46+2.4+1.14)=0.79*4=3.16
答
7.5*23+31*2.5=2.5*3*23+2.5*31=2.5*69+2.5*31=2.5*（69+31）=2.5*100=250
0.79*0.46+7.9*0.24+11.4*0.079=0.79*0.46+0.79*2.4+0.79*1.14=0.79*（0.46+1.14+2.4）=0.79*4=3.16