Do you know any short-cut????

[indian_girl]

Hi Pple.
Posting after a long time now....hope everyone is doing great and not studying too hard for CAT...well if u believe me i have worked very hard for CAT ...i have managed to complete (nd also understood finally) 1 chapter since 1 year now......planning to crack the so called CAT atleast by 2010 lol...well will not bore u anymore...lets come to the point...this thread is basically to share any shortcut methods that we know which can make our calculations easier and most importantly can maximise the speed of solving those tricky mathematical questions......( well i do hope dat the moderators dont shut down this thread .pls dont !!!!.. )....but anyways let me share one of the short -cuts that i know with u guys.....

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How do u find out whether a number is a prime number or not???? any guesses???

say for example how will u find out if 1517 is a prime number or not???

just find out the nearest possible square roots of the number ....like in the above case the nearest possible square roots for 1517 are 38 or 39 ( yes i used calculator ...lol)

We will always consider the highest possible sqaure root i.e in this case we shall consider 39...now divide 1517 by all the prime numbers </=39

1517 is divisible by 37 so it is not a prime number !!! yipee !!!

[HarshaRocks]

Hey,
You might like to share your stuff here
http://www.pagalguy.com/forum/prep-r...u-section.html (Neha's *Fundu* Section)
http://www.pagalguy.com/forum/prep-r...doc-other.html (Neha's maths funda doc and other CAT goodies..)

[rmbt]

Originally Posted by indian_girl

Hi Pple.
Posting after a long time now....hope everyone is doing great and not studying too hard for CAT...well if u believe me i have worked very hard for CAT ...i have managed to

!!!

Please use the SEARCH function to locate the relavent threads before starting a new thread:

http://www.pagalguy.com/forum/search.php


Post on the links posted above by HarshaRocks or these ones:
http://www.pagalguy.com/forum/quanti...ystem-417.html (Number System)

http://www.pagalguy.com/forum/quanti...hread-117.html (The Official CAT 2007 Quant Thread)

http://www.pagalguy.com/forum/quanti...athon-226.html (Quant Marathon)


All the best.

[bharathraj1]

Originally Posted by indian_girl

How do u find out whether a number is a prime number or not???? any guesses???

say for example how will u find out if 1517 is a prime number or not???

just find out the nearest possible square roots of the number ....like in the above case the nearest possible square roots for 1517 are 38 or 39 ( yes i used calculator ...lol)

We will always consider the highest possible sqaure root i.e in this case we shall consider 39...now divide 1517 by all the prime numbers </=39

1517 is divisible by 37 so it is not a prime number !!! yipee !!!

whoa!! that was some shortcut

lets say the guys who set the paper are not so generous and they give me a number 1467893 and ask me to find out if it is prime.
how am i gonna find the nearest square.

i think u can refer some threads that rmbt and harsharocks have pointed out, it might be of help



bharath