75×102
=75*(100+2)
=75*100+75*2
=7500+150
=7650
1.2×2.5
=(1+0.2)*2.5
=1*2.5+0.2*2.5
=2.5+0.5
=3
90.1-9.9
=(90+0.1)-(10-0.1)
=90+0.1-10+0.1
=80+0.2
=80.2
90.1×9.9
=(90+0.1)*(10-0.1)
=900-9+1-0.01
=908-0.01
=907.99
3.54×99+3.54
=3.54*99+3.54*1
=3.54*(99+1)
=3.54*100
=354
272÷125
=272*8/125*8
=2176/1000
=2.176
五年级上册简便计算