簡便算灋75×27+19×25=?
75×27+19×25
=(25×3)×27+19×25
=25×(3×27)+19×25
=25×81+19×25
=25×(81+19)
=2500
(-5.25)x(-4.73)-4.73x(-19.75)-25x(-5.27)怎麼求?
(-5.25)*(-4.73)-4.73*(-19.75)-25*(-5.27)
=(-4.73)*[-5.25+(-19.75)]-25*(-5.27)
=(-4.73)*(-25)+(-25)*(-5.27)
=(-25)*(-10)
=250
三十又二十八分之一乘二十九分之二十八(能否簡便方法)
先約去28,然後(30*28+1)/29=29