Don't trust MS Excel when it comes to accuracy

[DA74254]

So, I found out that MS Excel has the GammaLN function.
In the WP43 manual, there is an example on how to use the GammaLN to calculate really large Factorials (X!).

Both Excel and Libreoffice Calc claims to have 15 digits accuracy. Not remotely as accurate as SM/WP calcs, of course.

Anyway, just to test the routine, I dialled in GammaLN(51) in order to calculate 50!.
While the corrct answer, confirmed with both Free/Plus42 and WP43, is about 3,041409320171338x10^64, Excel comes up with 3,0044...x10^64.
Libreoffice comes up with: 3,04140932017131x10^64.
Notice that the last digit (1, instead of 3) is incorrect. Excel cr*pped out at the second digit..

Code used for the routine:
GammaLN(51)/LN(10)
FP
10^FP

Or, to put it in RPN routine:

Code:


LBL 'BigFac'
1
+
lnGamma
10
ln
/
Enter
IP
x><Y
FP
10^x
RTN
END

Note that this code works on WP43 or C47
The "1+" is so that you insert the number you would factorial (Gamma+1=X!).