3.333×3.333
=3.333×（3+0.3+0.03+0.003）
=9.999+0.9999+0.09999+0.009999
=10-0.001+1-0.0001+0.1-0.00001+0.01-0.000001
=11.11-0.001111
=11.108889
6.3÷4.2
=2.1×3÷（2.1×2）
=3÷2
=1.5