How many calibers require the type LB/RN?
CREATE TABLE table_21538523_1 (caliber VARCHAR, type VARCHAR)
SELECT COUNT(caliber) FROM table_21538523_1 WHERE type = "LB/RN"
### 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"