9.9×6.3+0.63
=9.9×6.3+6.3×0.1……变一变就简便
=6.3×(9.9+0.1)
=63
10.1×8.5-0.83
=(10+0.1)×8.5-0.83
=85+(0.85-0.83)
=85+0.02
=85.02