a count
Knowing how much weed you can get for a certain price. It's like knowing how much pizza you can eat for $5.
I did a count at the weed store. I got 10 grams for $20. That's a deal.
That guy did a count and got 5 grams for $10. I only got 2 grams for $10. He's better at counts than me.
That weed store does a count every day. They know exactly how much weed you can get for $10.