HP 10BII Combination Permutation

[Gamo]

HP 10BII+ got this functions but not for the HP 10BII

HP 10BII User Manual doesn't provide the way to calculate this and
here is my attempt.

Formulas:

Permutation: nPr = n! ÷ [ (n - r)! ]

Combination: nCr = n! ÷ [ r! x (n - r)! ]

Example:

6P3

6 [-] 3 [=] [n!] [÷] 6 [n!] [SWAP] [=] display answer 120

6C3

6 [-] 3 [=] [n!] [x] 3 [n!] [=] [÷] 6 [n!] [SWAP] [=] display answer 20

Remark:

The Factorial Function limit is up to 253! = 5.17 E499


Gamo 7/2021