I have a list of over 3000 people that bought products in different zip codes.

The spreadsheet is set up like below:

30044 1
30044 1
30125 1
11253 1

Th first numbers are the zip code and in the cell next to it, the number 1
represents a boought product in that zip code. Being that I have a list of
over 3000, how can I make a function that will total up how many products
were sold in each zip code???