Do Teachers Understand Math?

Do teachers really understand mathematics, or do they go through the motions?  I'm guessing most math teachers know how to do math, but as I grew as a mathematician I began to see the beauty in math and wondered why I haven't seen it before.  If you are curious like me on how good you are at math and numerical sense you take a quiz.  Unfortunately, I saw this on Friday night when I recorded some show on the science channel (that is how awesome I am) about how you perceive certain things in your brain more than others.  Before you see your results take the quiz here: http://panamath.org/testyourself.php

Before you look at my results and start comparing the two together and take my job, do you think your students can benefit from this test?

Apparently since I took the test, I am just as average as anybody else when it comes to mathematical sense and numerical sense.  Here is my graph:

Apparently I have an awful response time to these questions, but I was not in the 90th percentile for performance.  Would this make me a worse teacher than someone who scored higher than I did?  I'm not sure.  If you took the test and would like to share them below, please do.

Lastly, if you are still reading I came across an interesting blog for math teachers.  http://mathmistakes.posterous.com/ it is a blog that shows students math mistakes (without giving away their identity).  It asks questions like what mistakes they made?  How do you go back to these students and explain what mistakes or what they were doing wrong?  It goes over misconceptions and common mistakes that students have.  During the summer it is a great way for teachers to brush up on their grading skills and reach into student thinking.  I will be using this all summer long.  

Below is an example of one of the blog posts, does the student come up with the right answer?  What mistake did he/she make?  What would you say to him/her?