Plunkster82 wrote:

One thing I try to remind myself is that squares are rectangles.

-So I started with a square with sides of 5, area would equal 25. I chose 5 as the size of the sides because it's easy to increase and decrease by 20%.

-Length is increased by 20% 5+1=6.

-Width is decreased by 20%, 5-1=4

-New area is 4*6=24.

-(24-25)/25=-1/25=-4%.

-My biggest problem is dumb mistakes, if positive 4% was an answer, I might have chosen it. If anyone has any advice on dumb mistakes, please share.

Plunkster82 , there are threads here (and info elsewhere) that answer your question.

My two cents':

1) check your answers. On this kind of question, try different numbers. The square as rectangle is a great idea. But with percentages, try to use values such as 10 and 100 that give you a base of 100. Try 10 here as original L and W. You'll get 96 vs 100: Four percent smaller.

2) write down all but the most simple things, neatly. One of my favorite experts at gmatclub is a fan of mental math. I am not.

3) Check out these threads:

Tip of the Week, posts from Brian Galvin at

Veritas Prep and great links from

Bunuel:

HEREAnother,

HEREAnother,

HEREAfter those, I would run two Google searches with these terms:

1) GMAT dumb silly mistakes gmatclub; and

2) same, but omit "gmatclub"

Hope it helps.

_________________

In the depths of winter, I finally learned

that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"