题目内容：

简算：19.99乘19.98-19.97乘19.96

优质解答

19.99*19.98-19.97*19.96=(19.97+0.02)*19.98-19.97*(19.98-0.02)=(19.97*19.98+0.02*19.98)-(19.97*19.98-19.97*0.02)=19.97*19.98+0.02*19.98-19.97*19.98+19.97*0.02=0.02*19.98+19.97*0.02=0.02*(19.98+19.97)=0...