lol .. ok but check you calculator or any calculator , the log on it is base 10 , check all the references and books , log is base 10 ,, any other base you should specify . > Mostafa Ghalayini
B.E Computer and Communication engineering
M.S.E Computer and Communication engineering
Actually, it is common practice in advanced math books (Calculus or higher) to use just "log" to mean natural logarithm since common logarithms are seldom if ever used. The practice in more basic books is use "log" to mean common logarithms and "ln" to mean natural logarithms. Here, the question was posted in "Pre-Calculus" so I would have assumed that common logarithms were meant, but it is certainly not true that "log" always means common logarithm.
In any case, it would have been better if the original post had specified which logarithm was intended and if the responders had said which convention they were using!