quick question about log

hi
i'm working on an assignment and i'm suppose to take the log of a number , on the assignment sheet it looks like this:

log( totalAmount) - 1

my question is how do i write log in c++ ? like i know to get a number to the second power x it will be something like (pow(number), x)

so anyone who can help is welcome

log in c is written

Code:

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#include <math.h>

a = log(b);

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which gives the natural log of b. If you need to convert it to soem other base then simply divide the natural log of b by the natural log of the base you want and it gives you the log of b in that base.