log10() : log of a number to the base 10

log10(x) 

Example

#include <stdio.h>
#include <math.h>
int main(void){
     double  x,ret;
     x=2.7;
     ret=log10(x);
     printf("log10(%.2f)=%.2f", x,ret);
     return 0;
}

log10(2.70)= 0.43