Prime Numbers: 1 TO 20
Prime numbers between 1 to 20
Prime numbers are the numbers that have only two factors which are the number itself and 1. Eight prime numbers are present between 1 to 20. Now, any number that has more than two factors is called a non-prime ( composite) number. The number 1 is neither a prime nor a composite number.
The eight prime numbers between 1 to 20 are 2, 3, 5, 7, 11, 13, 17, 19.
How do we know that they are prime numbers?
The conditions of a number being a prime number are:
- The number must be divisible by itself and 1.
- It shouldn’t have any other factors.
Now,
2 = 2 x 1
3 = 3 x 1
5 = 5 x 1
7 = 7 x 1
11 = 11 x 1
13 = 13 x 1
17 = 17 x 1
19 = 19 x 1
The above numbers satisfy the condition of being a prime number.
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Frequently Asked Questions
Q1. Is 4 a prime number?
Ans: 4 has the factors 1, 2 and 4. It does not satisfy the conditions of a prime number as it has more than 2 factors.
Q2. Is 13 a prime number?
Ans: Yes. There are only two factors of 13, they are 1 and 13 itself.
Q3. What is the sum of the prime numbers from 1 to 20?
Ans: the prime numbers from 1 to 20 are 2, 3, 5, 7, 11, 13, 17, 19. The sum is 2+3+5+7+11+13+17+19 = 77. Therefore, 77 is the sum of the prime numbers from 1 to 20.