Question

Number of prime numbers from 1 to 50 are:
a) 18
b) 12
c) 15
d) 20

Answer 1

Hint: Before solving this question, we must know that meaning of prime numbers and composite numbers:-
PRIME NUMBERS: A number that is divisible only by itself and 1 is called a prime number. For example: 2, 3, 5, 7, etc. are prime numbers. A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers.
COMPOSITE NUMBER: A natural number greater than 1 that is not a prime number is called a composite number. In other words, a number that has more than two factors is called a composite number. For example: 4, 6, 8, 9, etc. are composite numbers.

Complete step-by-step answer:
Now, as we know what are prime numbers and composite numbers, we can solve this question.
So, there are 15 prime numbers from 1 to 50. That means, there are 15 numbers between 1 and 50 that have just two factors, i.e. 1 and the number itself.
They are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43 and 47.

Now, we can observe that the numbers written above have only two factors, that are 1 and the number itself.
For example: 11. We can see that 11 have just two factors, 1 and 11.
29 also has just 2 factors, 1 and 29.
So, we can say that the number of prime numbers between 1 and 50 are 15.
Therefore, the answer of this question is (c) 15.

Note: The student must remember about prime numbers and composite numbers as they can come in handy.
The following things should be kept in mind while doing such questions
PRIME NUMBERS: A number that is divisible only by itself and 1 is called a prime number. For example: 2, 3, 5, 7, etc. are prime numbers. A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers.
COMPOSITE NUMBER: A natural number greater than 1 that is not a prime number is called a composite number. In other words, a number that has more than two factors is called a composite number. For example: 4, 6, 8, 9, etc. are composite numbers.