Program in C to find square root of a number by using simple calculations

Write a program in C to find square root of a number by using simple calculations

#include <stdio.h>

#include <conio.h>

main()

{

            float a,b,e=0.00001,p,k;

            clrscr();

            textcolor(GREEN);

            do {

                        printf("*******************************************************");

                        printf(" PROGRAM TO FIND SQUARE ROOT OF A NUMBERxDB");

                        printf("*********************************************************");

                        cprintf("ENTER A NUMBER(-1 to Quit) :");

                        scanf("%f",&k);

                        a=k;p=a*a;

                        while(p-k>=e)

                        {

                                    b=(a+(k/a))/2;

                                    a=b;

                                    p=a*a;

                        }

                        printf("SQUARE ROOT IS = %f",a);

                        getch();

                        clrscr();

            }

            while(k!=-1);

            getch();

}