Question

199.4*19.93-199.3*19.92的简便计算

Answer 1

199.4×19.93-199.3×19.92

=(199.3+0.1)×19.93-199.3×(19.93-0.01)

=199.3×19.93+19.93×0.1-199.3×19.93+199.3×0.01

=1.993+1.993

=(2-0.007)+(2-0.007)

=4-0.014

=3.986