Nice! Useless but fun example: ln 125 is approximately lg 125 - log 125 ~= lg 128 - log 100 = 7 - 2 = 5. Exact answer is close to 4.83, less than 5% error witho

Nice! Useless but fun example: ln 125 is approximately lg 125 - log 125 ~= lg 128 - log 100 = 7 - 2 = 5. Exact answer is close to 4.83, less than 5% error without ever thinking about a fractional value root or log.