/sci/ - Science & Math

Here's some simple tree graphs showing why 7 isn't possible
The key in the top-left shows all possible numbers for each position, and the trees show how each potential combination will eventually fail (either by reusing a number or running out of valid numbers to use)

The closest combinations are 351624(7) and 571624(3), but they obviously don't fulfill the requirements of both A and B. I'm fairly confident 6 also fails, which means 8 is indeed the minimum