You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Comcast

Context:
In 1963, Ralph J. Roberts in conjunction with his two business partners, Daniel Aaron and Julian A. Brodsky, purchased American Cable Systems as a corporate spin-off from its parent, Jerrold Electronics, for US $500,000. At the time, American Cable was a small cable operator in Tupelo, Mississippi, with five channels and 12,000 customers. Storecast Corporation of America, a product placement supermarket specialist marketing firm, was purchased by American Cable in 1965. With Storecast being a Muzak client, American Cable purchased its first Muzak franchise of many in Orlando, Florida.

Question:
How many customers did ACS have when Roberts and his partners purchased it?

12,000