Patrick B. answered • 02/11/21
Math and computer tutor/teacher
33*32*31*30 * .... * 5*4*3*2
8.68331761881188649551819440128e+36 says the windows calculator
MS Excel says 8.68322 x 10^36
multiplying them in pairs:
33*32 = 1056
31*30 = 930
29*28 = 812
27*26 = 702
25*24 = 600
23*22 = 506 <--- the product down to here is 169,958,063,987,712,000
21*20 = 420
19*18 = 342
17*16 = 272
15*14 = 210
13*12 = 156
11*10 = 110 <-- 140,792,940,288,000 = 420*342*272*210*156*110
9*8 = 72
7! = 5040 <--362,880
169,958,063,987,712,000 * 140,792,940,288,000 * 362,880 =
(1.69958063987712 * 10^17) * (1.40792940288 * 10^14) * (3.6288 * 10^5)
so the power of 10 is in fact 36 = 17+14+5...
the problem is multiplication of these base mantissas without losing significant digits
window's calculator says: 2.3928895554486018781741056
8.68331761881188649551819440128 is the final result
which is 29 digits...
so if if you believe that result, then just throw out the decimal and add
7 zeros onto the back end to get your answer:
8683317618811886495518194401280000000
