#include<bits/stdc++.h>
using namespace std;

const int MAXN=5050;
const long long mod=998244353;
char ch[MAXN];
double L[MAXN];
int I[MAXN],A[MAXN],B[MAXN],C[MAXN],pd[MAXN];
int x[MAXN],y[MAXN],lenx,leny;
int len,le; 

void change(int len,int m)
{
	int x,pre,i;
	le=0;
	memcpy(B,A,sizeof(A));
	while(len)
	{
		x=0;
		for(i=len;i;i--)
		{
			pre=x;
			x=(x*10+B[i])%m;
			B[i]=(pre*10+B[i])/m;
		}
		C[++le]=x;
		while(len&&B[len]==0)
			len--;
	}
}

int calc(int m)
{
	change(len,m);
	if(le>m)
		return (I[m]-I[m-1]+mod)%mod;
	if(le<m)
		return 0;
	int i,j,ans;
	for(i=0;i<m;i++)
		pd[i]=0;
	ans=0;
	for(i=1;i<C[le];i++)
		ans=(ans+I[le-1])%mod;
	pd[C[le]]=1;
	for(i=le-1;i>0;i--)
	{
		for(j=0;j<C[i];j++)
		{
			if(pd[j]==0)
				ans=(ans+I[i-1])%mod;
		}
		if(pd[C[i]])
			break;
		pd[C[i]]=1;
		if(i==1)
			ans=(ans+1)%mod;
	} 
	return ans;
}

int calc()
{
	if(len==0)
		return 0;
	int ans,where,i;
	ans=0;
	where=2;
	while(L[where]<=len-1)
		where++;
	if(where<=15)
	{
		for(i=2;i<=15;i++)
			ans=(ans+calc(i))%mod;
		return ans;
	}
	for(i=2;i<=where-2;i++)
		ans=((ans+I[i]-I[i-1])%mod+mod)%mod;
	ans=(ans+calc(where-1)+calc(where))%mod;
	return ans;
}

int main()
{
	int i,T,lenx,ans;
	len=1;
	while(L[len]<MAXN)
	{
		len++;
		L[len]=log(len)/log(10)*(len-1);
	}
	I[0]=1;
	for(i=1;i<MAXN;i++)
		I[i]=I[i-1]*1ll*i%mod;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%s",ch+1);
		len=strlen(ch+1);
		for(i=1;i<=len;i++)
			A[i]=ch[len-i+1]-'0';
		lenx=len;
		for(i=1;i<=len;i++)
			x[i]=A[i];
		A[1]--;
		for(i=1;i<=len;i++)
		{
			if(A[i]<0)
			{
				A[i+1]--;
				A[i]+=10;
			}
		}
		while(len&&A[len]==0)
			len--;
		ans=calc();
		scanf("%s",ch+1);
		len=strlen(ch+1);
		for(i=1;i<=len;i++)
			A[i]=ch[len-i+1]-'0';
		leny=len;
		for(i=1;i<=len;i++)
			y[i]=A[i];
		ans=(calc()-ans+mod)%mod;
		printf("%d\n",ans);
	}
}