1.08-0.8=1.08-1+0.2=0.28
(0.18+0.9)÷9
=0.18÷9+0.9÷9
=0.02+0.1
=0.12
6.3÷0.01
=(6.3×100)÷(0.01×100)
=630÷1
=630
4.9×9+4.9
=4.9×(9+1)
=4.9×10
=49