Want to know the answer to this question? Check this out and find out.
According to usingaborrowedlanguage.com, the word series can be singular or plural depending on its usage. It stated that according to The American Heritage Dictionary, “Series is both a singular and a plural form. When it has the singular sense of “one set,” it takes a singular verb, even when series is followed by of and a plural noun: A series of lectures is scheduled. When it has the plural sense of “two or more sets,” it takes a plural verb: Two series of lectures are scheduled: one for experts and one for laypeople.”
For more info on this topic, please click here.