The explanation on Number system useful for Quantitative aptitude test. Also practice the questions.Will be updated and More set of questions will be added for Practice.
Natural numbers :
Natural numbers :
The numbers used for counting is called natural numbers. They are 1,2,3,4,5,..........
Odd Numbers :
The number which cannot be divisible by 2 are odd numbers. They are 1,3,5,7,9......
Even Numbers :
The numbers which can be divisible by 2 are Even Number. They are 2,4,6,8,.....
Whole number :
Also called counting number. one of the positive integers or zero; any of the numbers
Prime Number :
The number which can be divisible only by 1 is called prime number. 1 is exclusive from prime number. The numbers are 2,3,5,7,11.........
Composite Number :
The number other than 1 and not a prime number comes under Composite Number
1 is it is neither a prime nor a composite. The number 2 is the only integer that is prime and even number.
Rational Number :
A rational number is a number that can be written as a ratio. For example 8 is a rational number because it can be written as the fraction 8/1.
Let a/b is a rational number. here b=0
Irrational Number :
The number which cannot be written in the form of ratio. Irrational numbers cannot be represented as terminating or repeating decimals.
√2 is an irrational number
Addition Operation
n= n(n+1) for 1 to n numbers
2
n= Last Even number ; n= n(n+1) for 1 to n even numbers
2
Sum of n odd numbers = [(n+1)/2]2
Sum of Mth Term = M n(n+1)
2
Sum of squares of n -natural numbers = n(n+1)(2n+1)
6
Sum of cubes of consecutive n-natural numbers = [n(n+1)/2]2
For Practice Problems : Click Here
Addition Operation
Addition is the operation for finding the values of two numbers together. The result obtained by adding two or more numbers is termed as sum. Every set of aptitude contains addition problems. For solving the problem needs practice.
Eg: 4 5 6 3 6
5 7 3 1 9
2 4 9 8 1
12 7 9 3 6
Subtraction Operation
It is difference between the two numbers. The sign used for subtraction is - The aptitude question consists of combined addition and subtraction.
The Progression
Sum of n natural
numbers
n= n(n+1) for 1 to n numbers
2
Sum of n even numbers
n= Last Even number ; n= n(n+1) for 1 to n even numbers
2
Sum of n odd numbers
Sum of n odd numbers = [(n+1)/2]2
Sum of Mth Terms
Sum of Mth Term = M n(n+1)
2
Sum of Squares of consecutive n-natural numbers
Sum of squares of n -natural numbers = n(n+1)(2n+1)
6
Sum of cubes of consecutive n-natural numbers
Sum of cubes of consecutive n-natural numbers = [n(n+1)/2]2
For Practice Problems : Click Here
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