[logn]

At least for those problems, I don't think it's about trying to slow down. It's about trying to poke holes in your answer and make sure it holds up to some testing.

The intuitive answer to the first problem is $.10 but if you take time to double check and add a dollar to that, you see it's wrong.

I don't think this is too different from programming... the time you take to re-read some code you just wrote and think like a compiler and mentally execute the edge cases, etc.

[collyw]

For me it was a case of reading the question properly, rather than skimming it and assuming you knew what it was asking.