Factorial with long in C#

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here

double fact = 1;
int i = 0;
do
{
i++;
fact *= i;
Console.WriteLine(i.ToString() + " = " + fact.ToString("#"));
}
while (i < 100);

        }
    }
}


// Output from http://rextester.com/

/*

1 = 1
2 = 2
3 = 6
4 = 24
5 = 120
6 = 720
7 = 5040
8 = 40320
9 = 362880
10 = 3628800
11 = 39916800
12 = 479001600
13 = 6227020800
14 = 87178291200
15 = 1307674368000
16 = 20922789888000
17 = 355687428096000
18 = 6402373705728000
19 = 121645100408832000
20 = 2432902008176640000
21 = 51090942171709400000
22 = 1124000727777610000000
23 = 25852016738885000000000
24 = 620448401733239000000000
25 = 15511210043331000000000000
26 = 403291461126606000000000000
27 = 10888869450418400000000000000
28 = 304888344611714000000000000000
29 = 8841761993739700000000000000000
30 = 265252859812191000000000000000000
31 = 8222838654177920000000000000000000
32 = 263130836933694000000000000000000000
33 = 8683317618811890000000000000000000000
34 = 295232799039604000000000000000000000000
35 = 10333147966386100000000000000000000000000
36 = 371993326789901000000000000000000000000000
37 = 13763753091226300000000000000000000000000000
38 = 523022617466601000000000000000000000000000000
39 = 20397882081197400000000000000000000000000000000
40 = 815915283247898000000000000000000000000000000000
41 = 33452526613163800000000000000000000000000000000000
42 = 1405006117752880000000000000000000000000000000000000
43 = 60415263063373800000000000000000000000000000000000000
44 = 2658271574788450000000000000000000000000000000000000000
45 = 119622220865480000000000000000000000000000000000000000000
46 = 5502622159812090000000000000000000000000000000000000000000
47 = 258623241511168000000000000000000000000000000000000000000000
48 = 12413915592536100000000000000000000000000000000000000000000000
49 = 608281864034268000000000000000000000000000000000000000000000000
50 = 30414093201713400000000000000000000000000000000000000000000000000
51 = 1551118753287380000000000000000000000000000000000000000000000000000
52 = 80658175170943900000000000000000000000000000000000000000000000000000
53 = 4274883284060030000000000000000000000000000000000000000000000000000000
54 = 230843697339241000000000000000000000000000000000000000000000000000000000
55 = 12696403353658300000000000000000000000000000000000000000000000000000000000
56 = 710998587804863000000000000000000000000000000000000000000000000000000000000
57 = 40526919504877200000000000000000000000000000000000000000000000000000000000000
58 = 2350561331282880000000000000000000000000000000000000000000000000000000000000000
59 = 138683118545690000000000000000000000000000000000000000000000000000000000000000000
60 = 8320987112741390000000000000000000000000000000000000000000000000000000000000000000
61 = 507580213877225000000000000000000000000000000000000000000000000000000000000000000000
62 = 31469973260387900000000000000000000000000000000000000000000000000000000000000000000000
63 = 1982608315404440000000000000000000000000000000000000000000000000000000000000000000000000
64 = 126886932185884000000000000000000000000000000000000000000000000000000000000000000000000000
65 = 8247650592082470000000000000000000000000000000000000000000000000000000000000000000000000000
66 = 544344939077443000000000000000000000000000000000000000000000000000000000000000000000000000000
67 = 36471110918188700000000000000000000000000000000000000000000000000000000000000000000000000000000
68 = 2480035542436830000000000000000000000000000000000000000000000000000000000000000000000000000000000
69 = 171122452428141000000000000000000000000000000000000000000000000000000000000000000000000000000000000
70 = 11978571669969900000000000000000000000000000000000000000000000000000000000000000000000000000000000000
71 = 850478588567862000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
72 = 61234458376886100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
73 = 4470115461512680000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
74 = 330788544151939000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
75 = 24809140811395400000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
76 = 1885494701666050000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
77 = 145183092028286000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
78 = 11324281178206300000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
79 = 894618213078297000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
80 = 71569457046263800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
81 = 5797126020747370000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
82 = 475364333701284000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
83 = 39455239697206600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
84 = 3314240134565350000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
85 = 281710411438055000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
86 = 24227095383672700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
87 = 2107757298379530000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
88 = 185482642257398000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
89 = 16507955160908500000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
90 = 1485715964481760000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
91 = 135200152767840000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
92 = 12438414054641300000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
93 = 1156772507081640000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
94 = 108736615665674000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
95 = 10329978488239100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
96 = 991677934870949000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
97 = 96192759682482100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
98 = 9426890448883240000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
99 = 933262154439441000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
100 = 93326215443944100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

*/