0.4×2.5+0.07××50的簡便算灋 是0.4×2.5+0.07×50的簡便算灋

0.4×2.5+0.07××50的簡便算灋 是0.4×2.5+0.07×50的簡便算灋

0.4×2.5+0.07×50
=0.4×2.5+1.4×2.5
=2.5×(0.4+1.4)
=2.5×1.8
=2.5×2×0.9
=5×0.9
=4.5