Counting license plates I would like to know how to find the total number of vehicles of a city using Number Plates in following conditions:
Number plate has following format:
AA 9999 (2 Alphabets followed by 4 numbers)
Each alphabet can combine with any of the alphabet (including self) and form the first part of the number plate.
Each combination (e.g. AA) can have numbers from 0000 to 9999 to it. 
Based on this, can you please let me know max. number of vehicles that can be registered without changing numbering system?
Thanks!
 A: Last year, there was a news article that spoke of the 'gross overspending' of a particular football team on new clothing. They said that the team bought enough clothing for a total of 32 different combinations. Why so many?
I was not impressed, nor mortified (except by the media). Looking into it, the team had 2 colors of helmet, jersey, pants, socks, and arm-covers (whatever they're called). So they had 2 complete uniforms. But when choosing what to wear, they had 2 choices of helmet, 2 choices of jersey, 2 of pants, 2 of socks, and 2 for their arms. In total, they had $2 \cdot 2 \cdot 2 \cdot 2 \cdot 2 = 2^5 = 32$ different choices.
What a gross overstatement.
Also, this is called the multiplication principle, and it's how you do this problem.
A: It is 26^2 * 10^4 = 6760000.  26 is the number of possible letters, 2 is the number of letters on the plate, 10 is the number of possible digits, 4 is the number of digits on the plate.  Now consider what if there are still 2 letters and 4 digits but the letters and numbers can be mixed together, for example "A11B59"?
