GMAT Math Trick

There are a lot of math tricks out there to help improve your quant score but who knows them all?  I had the chance to have some tutoring sessions with one of the co-founders of the gmat coach .  This guy had the best way to solve problems. I LOVED his approach to problems. If only I would have found him earlier. Sadly, I found him 1.5 weeks before my exam but during the time I worked with him, the tips helped out a lot!!
This is one of the tricks he showed me. 

How many of you all can do all these problems in less than 30 secs? Go ahead take a moment and try. When I first saw these, I wanted to say "really sir, you joking right". I had memorized a few of these but there was no way I was going to finish the calculations in a 30 secs or less.

Well here is the trick to quickly solving squares that end in 5.  I'm assuming everyone knows that 5^2  is 25.  All numbers that end in 5 that are squared will end in 25. Now to get the begining numbers, take the first number multiply by the next consecutive number. Join those to numbers together and you have your answer.

Yea, its hard to understand math with words right? lol .... lets do 15^2 as an example.   1*2=2, join 2 with 25 and you get 225.  Now lets look at 25^2. 2*3=6 now join that with 25 and you get 625.  Lets go ahead and do one more, 35^2.  3*4=12, now join 12 to 25 and you get 1225. Now try and complete the rest in 15 seconds.

Brilliant right?!? The gmat coach showed me a better way to approach problems. With his approach I began to find myself solving problems faster which allowed me to spend more time on the harder problems. His tutoring sessions were well worth the money. For those who are starting their gmat prep or for those who are looking to raise their quant score,  I would seriously consider checking him out. His approach makes everything so simple!!!

-Ms. HR