Natural Numbers:
Counting numbers1, 2, 3, 4, 5, 6, ..... are called Natural numbers. Natural numbers are same like the whole numbers except zero.The Natural numbers are classified into three types. They are,
(i).ONE
(ii).PRIME NUMBERS
(iii).COMPOSITE NUMBERS
(i).ONE
The number 1 is considered as neither the prime number nor composite number.
(ii).PRIME NUMBERS
A prime number is natural number which is divisible only by itself and one. Number 17 is a prime number since it is not exactly divisible by any number except itself and 1. On the other hand, 27 is not a prime number since it is exactly divisible without a remainder by 9 and 3. Number Zero (0) is NOT a prime number. The Numbers shown below includes all the prime numbers from 1 to 100.
1, 2, 3, 5, 7, 11, 13, 17, 19, 23,
29, 31, 37, 41,43, 47,
53, 59, 61, 67, 71, 73,
79, 83, 97
One of the way to determine whether a number is a prime number is to try dividing it evenly by either 2, 3, 5, and 7. Usually, if these numbers fail to divide evenly into the number, it is prime Number. The exceptions are the rare instances where the number is only divisible exactly by the number over 10.
Example:
1.Which of the following numbers is prime? 101, 117, 123, 147.
Solution:
101 is a prime number because it is divisible only by itself and one. 117, 123 and 147 are divisible by 3 , So these numbers are not a prime numbers.
2.Which of the following numbers is not prime? 59, 71, 123, 143.
Solution:
123 is not a prime number. It is divisible by 3.
(iii).COMPOSITE NUMBERS
A composite number is any natural number which is evenly divisible by a number other than 1 or itself. No number is both prime and composite.
Example:
(i). 75 is composite since it is evenly divisible by 5.
(ii). 24 is composite siince it is evenly divisible by 2 and 3.
(iii). 5,421 is composite since it is evenly divisible by 3.
Whole Numbers
All counting numbers together with number zero (0) form the set of Whole Numbers. 0 is divisible by any non-zero number, but No number is divisible by 0. Every whole number bigger than 1 is either a prime number or a product of prime numbers. And,
(i). 0 is the only whole number which is not a natural number.
(ii). Every natural number is a whole number.
Different types of Whole numbers:
(i).Prime numbers
A number is prime if it is > 1 and it is only divisible by 1 and itself. Prime numbers play an important role within the whole numbers because they are the primary components.
e.g..2,3,5,7,11,....
b.(ii). Composite numbers
A number is composite if it can be written as the product of two smaller whole numbers.
e.g.. 4(=2x2), 6(=2x3), 10(=5x2)....
(iii).Identities
The numbers 0 and 1 are neither prime number nor composite, they are just identities for respective operations.
Rounding whole numbers:
To round to the nearest ten means to find the closest number having all zeros to the right of the tens place. when the digit 5, 6, 7, 8, or 9 appears in the ones place, round up; when the digit 0, 1, 2, 3, or 4 appears in the ones place, round down.
Examples:
Rounding 219 to the nearest ten gives 220.
Rounding 165 to the nearest ten gives 170.
Rounding 380 to the nearest hundred gives 400.
Rounding 150090 to the nearest hundred thousand gives 200000.
Related Tags
Natural And Whole Numbers , whole and natural numbers , difference between Natural Numbers And Whole Numbers