Shrimp are sized using two numbers separated by a slash, something like 41/50 or 21/25. These numbers represent how many shrimp make a pound. So If you’ve got a 1-lb bag of “41/50 shrimp,” there should be 41 to 50 shrimp in that bag. Below is a handy reference chart for names, counts, and average weights.
Be sure to adjust your cook times accordingly, small shrimp cook almost instantly, and super colossal shrimp take their time.