Question

How many prime numbers are less than 100?

• A. \(20 \)
• B. \(22 \)
• C. \(24 \)
• D. \(25 \)
• E. \(23 \)

Hint:

To find primes in a range: - Use the Sieve of Eratosthenes for faster calculation - Remember: 1 is NOT a prime number

Answer 1

The Correct Option is D

Concept: A prime number is a number greater than 1 that has only two factors: 1 and itself. To count primes less than 100, we list or use known results.
Step 1: List all prime numbers less than 100.
\[ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, \] \[ 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, \] \[ 73, 79, 83, 89, 97 \]

Step 2: Count the numbers.
\[ \text{Total primes} = 25 \]