Tricks for fast Addition of numbers

Here is another post on basic quantitative aptitude techniques, particularly concerning shortcut techniques in integer  addition Some of these are very easy to follow, still if you are not able to get something, please use the comments box to start the discussion on that particular topic.

Trick 1 : Adding Consecutive Numbers

Any set of consecutive numbers can be added by this simple relation-
Sum = (Last Number – First Number + 1) * (First Number + Last Number)/2

For example, you need to add numbers from 30 to 40, then…
Using the above relation, we get, Sum = (40-30+1) * (40+30)/2 = 11*70/2 = 385

Trick 2 : Sum of Odd numbers from 1 to n

This one is very easy. Sum of odd numbers from 1 to n is ((n+1)/2)2.
For example, 1+3+5+7+9+11+13+15+17+19+21 = ((21+1)/2)2 = 112

Trick 3 : Sum of Even numbers from 2 to n

To find this, use this relation-
Sum = (n/2)*((n/2)+1)
For example, to find sum up to 100, use this relation-
Sum = (100/2) * ((100/2)+1) = 50 * 51 = 2550

However these tricks are pretty obvious and very small, but when used in competitive exams like CAT and UPSC, these can be valuable resource in reducing the time required per question.

Check out a few more related posts here-

  1. Quantitative Aptitude Techniques
  2. Syllogism Cheat Sheet

Getting Started with Oracle Certified Java Associate – OCA

So, as I was preparing for Java for a while, I thought it would be better to get certified by the developers of Java. So, I’ve decided to get certified with Oracle’s latest Java Certification Exam, starting with Oracle Certified Java Associate level exam. The information that I got to know about this exam so far is that this exam is conducted at Pearson Testing Center and costs about Rs 9000 including taxes. Anyone, who is serious about Java should take this exam, as it would give them a confidence over their programming skill.

If you are interested in giving this exam, you can see some sample questions and the syllabus of this exam at this link-

Download

I would also recommend using Enthuware Test series, once you feel you are fully prepared for exam.

Windows Live Writer Portable – 5MB Installer

I use Windows Live Writer to write my blog sometimes, and not only this, Windows Live Writer also helps me doing some basic HTML editing in WYSIWYG style. It is the best products ever made by Microsoft for Bloggers blogging on Windows Platform. The best part about Windows Live Writer is that its free of Cost!
But wait, the downside is that it comes with Windows Live Package which weighs around 130MB to download. Not everyone in this world has that good internet connection for such bulky downloads. So, here is something which is rather less known to people, that Microsoft also offers Windows Live Writer as Standalone Offline installer which is with file size as low as less than 5MB.

This version is however older, but does all the basic things required by a Blogger, so if you are working on a low speed internet connections, this is best for you. You can carry this amazing software as a portable in pen drive as well.