1.02×5.5
=(1+0.02)×5.5
=1×5.5+0.02×5.5
=5.5+0.11
=5.61
18.8×101-18.8
=18.8×101-18.8×1
=18.8×(101-1)
=18.8×100
=1880
2.5×4.4
=2.5×(4+0.4)
=2.5×4+2.5×0.4
=10+1
=11