I agree with everything except after doing this for 20+ years, I think of my estimate and then multiply by 3. I've been much better at hitting my estimates since doing that (but I still miss 75% of the time).
If you double a number and add 30% on top, you could just add 160% to start with, or multiply by 2.6. Since we are talking estimates, you would be similarly well served with just 3x :)
Yes, you're correct. I'm also, like many of the people on HN, familiar with the associative property of multiplication. It's just a humorous way of saying that taking your estimate and doubling it isn't gonna be enough.
