Math Is Fun Forum

Ok guys, I'm gonna compete in a math competition next Sunday. I've done lots of preparations, and I think I'm ready for it.

Thing is, this week, we had another competition at school. The questions were tough (like they were meant to be). This is where my problem occurs. There are at least 3~4 questions, where I could do it with an eye close, but I did it wrong. For an example, there was a question like this:

Which is the "middlest" day in 2006?

So I just thought. 2006 has 356 days. So I use (N+1)/2 to find the middle day. Answer was 183. Then I wrote down.

Jan 31, Feb 30, March 31, .... June 30.
I thought June 30 was the answer, but it was wrong because FEBRUARY ONLY HAS 28 DAYS!!! I was so mad at myself by giving away free point. Seeing that there are only 30 questions in that competition, one question could mean winning and losing. How could I forgot that February had 28 days. darn! Carelessness.....

There was also another question that asked the sum of 1+3+5+7...+25. And do you know what I calculated? I forgot it was only odd numbers, and used the formula, n/2(a+l) like this:

25/2(1+25)!!!!!

How do I cure it???? I mean my carelessness.:( Thanks.