There’s a subtraction equation written on the board, with three digits minus three digits, and the primary digits each mounted. Alice and Bob have to fill within the remaining 4 digits (A~D beneath) utilizing 4 turns to finish the equation. On every flip, Alice chooses a quantity from 0~9 given to Bob, then Bob chooses a digit house to place within the quantity given.

Alice’s aim is to make the ultimate distinction as giant as potential, and Bob’s aim is to make the ultimate distinction as small as potential. If each use the optimum technique and the 4 numbers Alice chooses have to be non-repeatable,

What’s the closing distinction?

    2 A B
  - 1 C D

This puzzle just isn’t formidable, although a bit simple to present a unsuitable reply. To maximise the enjoyable you get, no computer systems and giving your tried reply first (do not should publish it) earlier than checking others’, is really useful.