Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_27998152_1 (date_of_birth VARCHAR, previous_club VARCHAR)
### Question:
how many date of birts are if the previous club is chelsea
### Answer:
SELECT COUNT(date_of_birth) FROM table_27998152_1 WHERE previous_club = "Chelsea"