Re practical security I don’t think a drug addict or other thief is going to be trying to work out the combinatorial equation to your lock. They’ll break a window or kick in a door. An enterprising type might beat it with a sledge hammer after feeze spraying it to shatter it. The security of the combination pad is almost irrelevant.
IAAM but…
Notice that 321 is still 6.
I thought the original lock was 10 choose 10. Not 10 choose 4. I thought we established that already.
If it’s 10 choose 4, then the answer is 10987 or 5040, right?
If it’s 10 choose 2, isn’t the answer 109 or 90?
I think I see… yeah… if 4321 opens the 1234 lock then yeah, this isn’t very secure at all.