Last Digit / Units Digit 






To find the units digit of xy we only consider the units digits of the number x.
To calculate units digit of 237234 we only consider the units digit of 237. Hence, we find the units digit of 7234.
To find the units digit of a × b, we only consider the units digits of the numbers a and b.
To calculate units digit of 233 ×  254, we only consider the units digit of 233 and 254 i.e. 3  and 4, respectively. Hence, the units digit of 233 ×  254 = units digit of 3 × 4 i.e 2.

First digit of a Number

Problems for practice

1. Find the unit digit of [ 1020000 / ( 10100 +3) ] where [ x ] is greatest Integer less than or equal to x.
2. Find the unit digit of the product of first 120 primes .
3. What is the unit digit of 1! + 2! + 3! + 4! +….. + 2018! ?
4.  What is the unit digit of (1! + 2! + 3! + 4! +….. + 2018!)2?
5. What is the unit digit of 231001 ?

Some more ‘Gyan’ on numbers :
Nifty Formulae for Natural Numbers
Divisibility Rule of a Number (Divisibility Test)
Remainders theorem 
Divisors of a Number ( Number of Divisors of a number)

Do you know that we have a forum where you can get all your doubts cleared?

Important Concepts and Formulae


Hello CAT takers,

Now that we are just a few days away from CAT, you must be revising everything for one final time before CAT. Here is a compilation of all the important Concepts and formulae for Quant. Whether you need to revise the formulae or you need them while solving problems of different topics, it’s all at one place for your ready reference.

Download it and use it for your benefit. 

Important Concepts for CAT2018

The only certain thing about CAT is uncertainty!

We hope that you are already done with your preparation for CAT 2018. You must have revised the syllabus again and again to make yourself comfortable. We know it because we have heard it from….yes, literally everyone! However, many of you are preparing with books which were written 5-6 and in some cases 10 years ago. During this time period IIMs have changed their directors multiple times, as have their faculty members and, not to mention, their CAT test patterns and types of questions .

We at TathaGat observe, analyse and attempt the CAT paper every year to bridge the gap. With an in-depth analysis of the changing trends in CAT we have picked the most probable problems which expose you to all sorts of techniques used while framing a question. Practise them to your full strength during the last days of CAT preparation .

Solve these questions without any time limit. The answers are given on the last page. In case you find any difficulty you can ping us in the relevant forums ( without any hesitation .. we are always eager to help you out ..

Download the file from the link given below:  

101 Must Solve QA




PRIME NUMBERS : The Most Mysterious Figures in Math 

Prime numbers have always fascinated mathematicians. They appear among the integers seemingly at random, and yet not quite: there seems to be some order or pattern, just a little below the surface, just a little out of reach.
—Underwood Dudley

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. For example, 11 is a prime number because it has no positive divisors other than 1 and 11.

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Alphametics The Art of Numbers

As CAT 2018 preparation starts heating up, I am going to flag the race with an oddball topic: Alphametics. What are alphametics or cryptarithms as they are also known?

Alphametics are number puzzles in basic arithmetic operations where digits are represented by alphabets. It is customary that different digits are represented by different alphabets. Why are alphametics relevant? Because they require a good knowledge of the properties of numbers and skill in working with them. Solving alphametics helps you quickly identify the solution to many problems which might otherwise require a good amount of time.

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This lesson covers the fundamentals and types of nouns, knowledge of which will help you in B-school entrance exams like the NMAT, SNAP and IIFT.

So, let’s get started!

Noun: A noun is a word that is used to name a person, animal, place, thing, or an abstract idea. Nouns tell you about the ‘what’s’ ‘who’s’ and ‘where’s’ of a sentence. Let’s see an example: TG and Dagny went to Maxims to order a chocolate truffle cake.

TG and Dagny are persons, Maxims is a place and chocolate truffle cake is a thing.

Nouns can be broadly classified into

  • Common nouns
  • Proper nouns
  • Concrete Nouns
  • Abstract Nouns
  • Countable Nouns
  • Non-Countable Nouns
  • Collective Nouns
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Some properties of natural numbers :

1•Sum of first n natural numbers : 1 + 2 + 3 +……+ n = n ( n +1)/2

2• Sum of squares of first n natural numbers : 1² + 2² + 3² +……+ n² = n ( n +1) ( 2n +1) /6

3• Sum of cubes of first n natural numbers : 1³ + 2³ + 3³ +……+ n³ = [ n ( n +1)/2]²

4• Sum of first n odd numbers: n²

5• Sum of first n even numbers: n² + n

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Similar Triangles

Similar Triangles

The current article deals with a frequently occurring topic in geometry in CAT- similarity of triangles. Most of you will notice that this topic is coming year after year in CAT and, as geometry questions in CAT are easy compared with other topics, mastering the concept is easier than mastering concepts in Algebra, Permutation, and Combination, or Probability.

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