Number system is an important topic when you are preparing for the CAT examination. Students generally start their CAT preparation from this topic only, not because questions are asked from this topic in the exam but also because this topic is basis for many other topics. Many a time the questions of arithmetic require a good knowledge of the basic concepts of number system like types of numbers, prime numbers, divisibility rules etc. We’ve seen students often searching for topics like Important Number System Questions, or Number System PDF for CAT, we will be uploading all this in upcoming articles.

Following is the list of important topics in number system for CAT exam.

**2. Divisibility Rules**

**3. Factors of a number**

**4. Factorials including the concept of trailing zeroes**

**5. Remainders including Euler’s Theorem**

**6. HCF and LCM**

**7. Unit digit and last two digits of number**

While starting preparing for number system, the student should start with the types of numbers. You can never ignore the type of numbers as if we change the type say from natural numbers to integers, the whole answer of the question may change. Next divisibility rules are equally important as you can expect direct questions on divisibility rules or these can have application in other areas of quantitative aptitude.

Finding the factors of numbers is also an important concept from CAT examination perspective. Questions from this topic are frequently asked in CAT and other management entrance examinations. To solve the questions from this area you should have knowledge of prime numbers as prime factorisation of the numbers will be required to get the number of factors or the sum or product of factors of a number.

Remainders is another area of the number system where the questions were asked in past CAT papers. One should note that the questions asked from this area are of basic type which require basic knowledge binomial theorem and of Euler’s Theorem.

Next important area where the questions are frequently asked is HCF and LCM. Now this topic can have questions which are very basic and also which are advanced level where you might need to use algebra also. Also, the student should be very clear about the difference between factor and multiple of a number.

Unit digit and last two digits is the easier concept of the number system. The unit digit topic is based on the concept that the unit digit of the numbers with certain powers repeats after 4 steps. The concept of last two digit is an interesting concept and require sound knowledge of squares of numbers.

We will discuss all these topics in our next articles… So, stay tuned!!

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