#include<stdio.h>

char a,b,c;
int y,x,i,nr,j;
long t;
int v[100];

int main()
{
	freopen("cifra.in","r",stdin);
	freopen("cifra.out","w",stdout);
	scanf("%ld\n",&t);
	for (i=1; i<=99; i++)
	{
		x=1;
		for (j=1; j<=i; j++)
			x=(x*i) % 10;
		v[i]=x;
	}
	while (t)
	{
		scanf("%c%c",&a,&b);
		if (b=='\n') nr=1;
		else nr=2;
		if (nr==2) scanf("%c",&c); 
		else c='\n';
		while (c!='\n')
		{
			a=b; b=c; nr++;
			scanf("%c",&c);
		}
		if (nr>=2)
			x=(a-'0')*10+b-'0';
		else
			x=a-'0';
		y=0;
		for (i=1; i<=x; i++) 
		{
			y+=v[i];
		}
		printf("%ld\n",y%10);
		t--;
	}
	fclose(stdin); fclose(stdout);
	return 0;
}