Question

lg998的近似值

Answer 1

lg998=lg(1000-2)

=lg(1000(1-1/500))

=lg10^3+lg(1-1/500)

=3+lg(1-1/500)

=3+ln(1-1/500)/ln10

≈3-(1/500)/ln10(ln10=2.302585...)

=3-2/2302.585

=2.99913.