432.1×123.4-432.2×123.3
=432.1×123.4-432.1×123.3-123.3×0.1
=432.1×（123.4-123.3）-123.3×0.1
=432.1×0.1-123.3×0.1
=43.21-12.33
=30.88
回答完毕