Art of Problem Solving: Complementary Counting Part 2

Art of Problem Solving's Richard Rusczyk explains how to count what you want by counting what you don't want.

[cocomeows]

lol super funny and also helpful!


2021 anyone?

[jangwoo]

8:07 Really? You're looking at a board!

[lowkey-]

I got it :-) Thanks Alot.... I hope to practice these skills I learned....

[wontpower]

His shirt says Seattle, but it sounds like Schwarzenegger

[naveenmukkatt]

California: "Hasta la vista, baby!"

[Nobody-Nowhere-Nothing]

Why isn't it 26x25x24x23x22 for the ones we don't want

[ayushibansal]

What is wrong with my solution?

We need at least 2 letters to be same for the required license plates. So, I clubbed those 2 as one unit.
Now, we have 4 places _ _ _ _ and we can fill all of these with any of the 26 letters.
That gives us 26*26*26*26. Also, the clubbed unit can be placed at any of the four positions. So, the final ans becomes 4*(26^4) = 1, 827, 904.
Where am I wrong?

[jangwoo]

California, under governor Schwarzenegger?