2除以0.5-0.5除以2的簡便算灋

2除以0.5-0.5除以2的簡便算灋


2/0.5-0.5/2
=2/(1/2)-(1/2)/2
=2*2-1/2*1/2
=4-1/4
=3又3/4



0.99*9+0.99的簡便算灋


0.99*9+0.99
=0.99×(9+1)
=0.99×10
=9.9