Two points: a) If a person is using those values daily for years (or even a couple of months), then it's very likely they'd have memorized them b) Sometimes j

Two points: a) If a person is using those values daily for years (or even a couple of months), then it's very likely they'd have memorized them b) Sometimes just knowing the concept exists for sure is good enough, as you can then go and brute force things until you've worked out the values