Prime numbers are numbers that are divisible by one and itself or we can say that they have exactly two factors. These numbers only appear in the tables of 1 and the number itself. They do not appear in the table of other numbers.
Examples are: 2, 3, 5, 7, 11, and 13…… etc
Composite numbers are numbers that are not only divisible by one and itself but are divisible by other numbers as well or we can say they do not have exactly two factors but more number of factors. These numbers appear in the tables of various other numbers except one and the number itself.
Examples are: 4, 6, 8, 9, 12, 14, 16, and 18 ……….etc.
1 does not fall under the head of prime or composite number hence termed as co-prime number.
How can we find out whether a number is prime or composite?
Check the factors of the given number
There are two possibilities
Here is a list showing all the prime numbers
The numbers that are highlighted are prime numbers and the numbers that are not highlighted are called composite number.
1 is not highlighted but it is not a composite number it is a co-prime number as mentioned earlier.
One important thing to note from the grid of numbers given is that all the prime numbers are odd numbers except 2. That is why 2 is called the only even prime number as all other prime numbers are odd.
Examples of sum more prime numbers:
101, 103, 107, 109, 113, 127, 131, 137, 139, 149
Example:
Find the prime numbers from 50 to 60
Factors of 50 |
50 × 1 = 50 2 × 25 = 50 5 × 10 = 50 |
More than 2 factors; composite |
Factors of 51 |
51 × 1 = 51 3 × 17 = 51 |
More
than 2 factors; composite |
Factors of 52 |
52 × 1 = 52 26 × 2 = 52 13 × 4 = 52 |
More
than 2 factors; composite |
Factors of 53 |
53
× 1 = 53 |
2
factors; Prime |
Factors of 54 |
54 × 1=54 2 × 27 = 54 3 × 18 = 54 6 × 9 = 54 |
More
than 2 factors; composite |
Factors of 55 |
55 × 1 = 55 11 × 5 = 55 |
More
than 2 factors; composite |
Factors of 56 |
56 × 1 = 56 2 × 28 = 56 7 × 8 = 56 4 × 14 = 56 |
More
than 2 factors; composite |
Factors of 57 |
57 × 1 = 57 3 × 19 = 57 |
More
than 2 factors; composite |
Factors of 58 |
58 × 1 = 58 2 × 29 = 58 |
More than 2 factors; composite |
Factors of 59 |
59 × 1 = 59 |
2
factors ; Prime |
Factors of 60 |
60 × 1 = 60 6 × 10 = 60 2 × 30 = 60 3 × 20 = 60 4 × 15 = 60 12 × 5 = 60 |
More than 2 factors; composite |
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