|How many commas are required in this sentence?
Google was launched in September 1998 in Menlo Park California.
The correct punctuation for the sentence is Google was launched in September 1998 in Menlo Park, California.
You need a comma between the city and state.
With full dates (month, day, and year) you need to put a comma after the year if your sentence continues. If the day isn’t included, however, no comma is needed after the year.