Do you believe I have mind reading? Let's play a game together.
You see, there are 9 cards on the screen. You can pick a card at will, point your finger at it, and move your finger horizontally or vertically. For example, if you first point to spades A with your finger, then move one step to the right, your finger will point to spade 2, and then take another step down, and your finger will point to spades 5. Be careful not to walk diagonally.
The rules are clear, right? Now, mind reading has officially begun.
First, please choose a black card, note that it must be black. Then, point your finger at it!
Then, please follow the rules just now, walk 5 steps horizontally or vertically.
1，2，3，4，5
Well, keep your fingers from moving. I believe that your fingers now must no longer be on the A of Spades. So I took the A card off. Note: After removing it, the A card cannot be removed.
Next, please continue to move your fingers, starting from where you just stopped, and then take 4 more steps at will.
1，2，3，4
Well, keep your fingers. Your fingers must not be pointing at Plum Blossom 3 and Plum Blossom 7, and I removed them as well.
Please move your finger 3 more times. Again, the phrase: the position of the card that has been removed can no longer go.
1，2，3
All right. Your finger must not be on Peach 2, and I'll take peach 2 off as well.
Now with 5 cards left, please move your finger 2 more steps.
1，2
I guess your fingers aren't on Peach 4 and Peach 6, and I'll take them off as well. Now there are only 3 cards left, and your finger must be on one of them.
Finally, please move your finger 1 more step.
Good! Do not move your fingers. Your finger must not be on Spades 5 and Spades 9, you must be pointing to Block 8!
Did I guess correctly?
Do you know what the principle of mind reading is? It's actually quite simple.
Switch back to the original card and you'll notice that the red and black cards are spaced apart. If you move 1 step, you will definitely switch the color of the card, that is, red becomes black, or black becomes red; if you move 2 steps, the color will definitely switch back.
That is to say: when the number of steps taken is odd, the color of the pointing card will change, and the color of the card will not change when the number of steps taken is even.
At first I asked you to pick a black card and then move 5 steps, and I'm sure now you must be pointing to a red card so I can take out the A of Spades. Then I let you take 4 steps, and I was sure you were pointing to a red card, so I took out Plum 3 and Plum 7. Ultimately, by my rules, no matter which black card you initially picked, and no matter how you walked, you ended up with only one card, and that was block 8, do you understand?
Go and try it out with your little buddy!