Now assume you have learned that interest is actually compounded monthly,
which makes the equivalent annual interest rate different from 12 times the
monthly interest rate. Revise the readers and writers that you were asked
to devise in Segment 411 to accommodate monthly compounding.
You will need to include the line
#include <math.h> in your program,
because that line allows you to use the library function,
pow function takes two arguments, x and y, both of
double, and computes xy.