Correct Answer - Option 4 : 8
Given:
Prime numbers are there less than 20
Concept used:
Prime number are divisible only by the number 1 or itself.
Calculation:
A Prime number is a positive integer having exactly two factors. If T is a prime number, then it's only factor are necessarily 1 and T itself.
According to the question,
⇒ 2, 3, 5, 7, 11, 13, 17, and 19 are prime number in first 20 number.
⇒ 1 × 2, 1 × 3, 1 × 5, 1 × 7, 1 × 11, 1 × 13, 1 × 17, and 1 × 19 all number has two factor(1 and itself).
∴ 8 Prime number are there less than 20.
1. 1 is neither a prime number nor a composite number.
2. The only even prime number is 2.
3. No prime number greater than 5 ends in a 5.
4. 2 is only even prime number.
5. 1 to 100 total 25 prime number.
6. 1 to 50 total 15 prime number and 51 to 100 total 10 prime number.
