Ques: What is the sum of first five prime numbers?
To find the sum of the first five prime numbers, we first need to identify which numbers are prime. Prime numbers are those that only have two factors, 1 and the number itself. We can’t use a straightforward method to determine if a number is prime, so we need to think about the factors that a given number could have.
Starting with 1, we can see that it has only one factor, which is itself. Therefore, it is not a prime number. Moving on to the next few numbers, we find that 2, 3, 5, and 7 are prime, but 4, 6, 8, and 9 are not. Every even number (except 2) is a composite number, meaning it has more than two factors.
The first five prime numbers are 2, 3, 5, 7, and 11. To calculate their sum, we simply add them together:
2 + 3 + 5 + 7 + 11 = 28
Therefore, the answer is (d) 28.
Note: It’s worth noting that 2 is the only even prime number because it only has two factors: 1 and 2.