Hello aspirants, quick calculations in JEE, BITSAT, WBJEE, NDA, and other competition plays a very important role so to jump to the next question which gives a little time to attempt the next question and leads to maximize the score. Moreover, exams like JEE Numericals (Sections B) have proved that quick calculations are very important for quick marks in Numerical Section. So let’s see how to do so.

### Easy Guidelines

• First of all, don’t use calculator at all, using calculator will make you kind of addictive to use it and you will to feel the urge to use it  even in the middle of exams so do avoid it in early days only
• Second of all, you may develop (if possible) some small tricks for quick calculations.
• Thirdly, sometimes even after calculations also re-think that Is the calculated value acceptable?

For example

1. Question asked to calculate the area under the curve and your answer is more than 200 square units then it looks pretty odd
2. Question asked to calculate the number of moles and the result is like 500 then definitely your answer is wrong

## Some easy Shortcuts(eg)

Unit digit of different numbers end as follows:
Number Unit digit (before squaring)
Number Unit digit (after squaring)

• 0=0
• 1=1
• 2=4
• 3=9
• 4=6
• 5=5
• 6=6
• 7=9
• 8=4
• 9=1
• Too remember the divisibility rules of 2,3,4,5,6,7,8,9,11. Sometimes this helps too.
• Try to memorize the value of some most used constants,

go to this link for all constants à ( https://en.wikipedia.org/wiki/List_of_physical_constants )

Try to memorize the value of some more used  mathematical constants like powers of

e=2.73,
e^2=7.45,
e^3=20.34
And values of log2, log3, log5, log7,etc.

• ALWAYS REMEMBER THIS FORMULA