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_21538523_1 (caliber VARCHAR, type VARCHAR)
### Question:
How many calibers require the type LB/RN?
### Answer:
SELECT COUNT(caliber) FROM table_21538523_1 WHERE type = "LB/RN"