The number of prime numbers which are less than 100 is

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CDS - 2017

Quantitative Aptitude

The number of prime numbers which are less than 100 is

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CDS I 2017 General Knowledge Previous Year Paper (05-Feb-2017)

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The correct answer is

Finding Prime Numbers Less Than 100

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. To find the number of prime numbers less than 100, we need to list all such numbers starting from 2 and going up to 99, checking if each number meets the definition of a prime number.

Here is the list of prime numbers less than 100:

2 (only even prime number)
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97

Let's count the numbers in this list carefully.

Range	Prime Numbers	Count
1-10	2, 3, 5, 7	4
11-20	11, 13, 17, 19	4
21-30	23, 29	2
31-40	31, 37	2
41-50	41, 43, 47	3
51-60	53, 59	2
61-70	61, 67	2
71-80	71, 73, 79	3
81-90	83, 89	2
91-100	97	1

Adding the counts from each range:

$4 + 4 + 2 + 2 + 3 + 2 + 2 + 3 + 2 + 1 = 25$

There are 25 prime numbers less than 100.

Revision Table: Prime Numbers up to 100

Count	Prime Number
1	2
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	37
13	41
14	43
15	47
16	53
17	59
18	61
19	67
20	71
21	73
22	79
23	83
24	89
25	97

Additional Information: Understanding Prime Numbers

Understanding prime numbers is fundamental in number theory. Here are some related concepts:

Composite Number: A natural number greater than 1 that is not prime is called a composite number. Composite numbers have divisors other than 1 and themselves. Examples: 4 (divisors 1, 2, 4), 6 (divisors 1, 2, 3, 6).
Number 1: The number 1 is neither prime nor composite. It only has one divisor, which is 1 itself.
Sieve of Eratosthenes: This is an ancient algorithm used for finding all prime numbers up to a specified integer. It works by iteratively marking as composite (i.e., not prime) the multiples of each prime, starting with the first prime number, 2.
Importance: Prime numbers are the building blocks of all natural numbers greater than 1, as stated by the Fundamental Theorem of Arithmetic (every integer greater than 1 is either a prime number itself or can be represented as the product of prime numbers).

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More Questions from CDS

The following question consists of six sentences of a passage. The first and the sixth sentences are given in the beginning as S1 and S6. The middle four sentences in each have been jumbled up and labelled P, Q, R and S. You are required to find the proper sequence of the four sentences and mark your response accordingly.

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Finding Prime Numbers Less Than 100

Revision Table: Prime Numbers up to 100

Additional Information: Understanding Prime Numbers

Similar Questions

Important Questions from Integers

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Count	Prime Number
1	2
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	37
13	41
14	43
15	47
16	53
17	59
18	61
19	67
20	71
21	73
22	79
23	83
24	89
25	97

Count	Prime Number
1	2
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	37
13	41
14	43
15	47
16	53
17	59
18	61
19	67
20	71
21	73
22	79
23	83
24	89
25	97

Count	Prime Number
1	2
2	3
3	5
4	7
5	11
6	13
7	17
8	19
9	23
10	29
11	31
12	37
13	41
14	43
15	47
16	53
17	59
18	61
19	67
20	71
21	73
22	79
23	83
24	89
25	97