12.5x2.4一0.25x24简便方法

12.5x2.4一0.25x24简便方法

追答下面的做不追问做追答

12.5*2.4-2.5*2.4
=2.4*（12.5-2.5）
=24

=12.5x(2.4-2.4)
=0追答=12.5x(2.4-2.4)
=12.5x0
=0

第一个,12.5*2.4-0.25*24 = 0.25*10*2.4-0.25*24=0.25*(10*2.4)-0.25*24=0.25*24-0.25*24=0(乘法结合律)
第二个,3.54*0.4/3.54*0.4=3.54/3.54*0.4*0.4=0.16(乘法交换律)
第三个,(5-0.3)*0.45+0.09=5*0.45-0.3*0.45+0.3*0.3=5*(0.3*1.5)-0.3*0.45+0.3*0.3=0.3*(7.5-0.45+0.3)=0.3*7.35=2.205(这题好像你抄错了)

12.5x2.4一0.25x24
=12.5×2.4-2.5×2.4
=2.4×（12.5+2.5）
=2.4×15
=36
3.54×0.4×1/3.54×0.4
=0.16
4.7×0.45+0.09
=47×0.045+0.09
=0.045×（47+2）
=0.045×49=2.205追问
简便方法追答=（0.13+0.13+0.13+0.13）×0.5
=0.13×4×0.5
=0.13×2
=0.26
这个答案正确，请采纳吧

(1)
12.5x2.4-0.25x24
=24x(1.25-0.25)
=24x1
=24
(2)
3.54x0.4÷3.54x0.4
=(3.54÷3.54)x0.4x0.4
=0.4x0.4
=0.16
(3)
(5-0.3)x0.45+0.09
=0.09x[(5-0.3)x5 +1]
=0.09x[ 23.5 +1]
=0.09x 24.5
=2.205