#include <stdio.h>
#include <stdlib.h>

unsigned int mult(unsigned char *s,long n);
disp(unsigned char *s);

main()
{
	unsigned char val[60500] = "\x2";
	unsigned int l,a;

	srand(clock());

	a = 0;
	do {
		a++;
		l = mult(val,2);
		printf("2^%-7u = ",a,l);
		disp(val);
		printf("                 (%u digits)\n",l*2 + ((val[l-1] < 11) ? -1:0) );
	} while (l < 60450 && (!kbhit() || getch() != 27));

	return 0;
}


disp(unsigned char *s)
{
	unsigned int a;
	unsigned int t,t2;
	unsigned int c,d,e;


	t2 = a = strlen(s);
	c = t2 * 2;
	if (s[a-1] < 11) c--;
	c %= 3;
	if (c == 0) c = 3;
	d = 3-c;

/*      l c d
  1,000 4 1 2
 11,000 5 2 1
111,000 6 0 0
 */

	printf(" ");
	d = 3-c;
	if (d) for (;d;d--) printf(" ");
	d = -1;

	while (a) {
		a--;
		t = (s[a]-1);
		if (a != t2-1 || t/10 != 0) {
			printf("%d",t/10);
			if (--c == 0 && a != 0) {
				c = 3;
				printf(",");
				if (++d == 15) {
					printf("\n                 ");
					d = 0;
				}
			}
		}
		printf("%d",t%10);
		if (--c == 0 && a != 0) {
			c = 3;
			printf(",");
			if (++d == 15) {
				printf("\n                 ");
				d = 0;
			}
		}
	}
	printf("\n");
	return 0;
}

unsigned int mult(unsigned char *s,long n)
{
	unsigned int a;
	unsigned long c;

	c = 0;
	for (a=0;s[a];a++) {
		c += (s[a] - 1) * n;
		s[a] = 1 + c % 100;
		c /= 100;
	}
	while (c) {
		s[a] = 1 + c % 100;
		c /= 100;
		a++;
	}
	s[a] = 0;
	return a;
}