Stupid question from stupid non-math-orientated person here.

I have a list of four-digit sequences. These sequences consist of and iterate through a letter of the alphabet followed by a range of numbers from 100-999. So the list starts at A100, followed by A101, A102... A999, B100, B101... right up to Z999. Assuming each number in the list is unique and there are no repeats, how many permutations does that result in? How would I calculate it?

I had initially thought it was as simple as:

*Letters in alphabet x Range of numbers*

or

# $26 * 899 =$ 23,376 numbers

...but on looking deeper into the maths behind permutations and combinations I feel like I may have made a stupid assumption there. If I have and my initial calculation was wrong, how exactly would I go about doing this?