Question & Answer

What is the sum of the smallest prime and largest prime number less than 10?
A. 7
B. 9
C. 10
D. 11
E. 12

ANSWER Verified Verified
Hint: Find the smallest and largest prime number between the numbers 1 to 10. Thus add both the values obtained.

Complete Step-by-Step solution:
Prime numbers are the positive integers having only 2 factors that is 1 and itself. For example 6, its factors are 1, 2, 3 and 6, which has 4 factors in total. But if we are taking the number 11, the only factors are 1 and 11. Thus 11 is a prime number but 6 is not a prime number, it’s a composite number.
We know that 1 is neither prime nor composite.
Now let us write the prime numbers from 1 to 10.
The prime numbers are = 2, 3, 5, 7.
These are 4 prime numbers between the numbers 1 to 10. Out of these we can see that 2 is the smallest prime number and 7 is the largest prime number.
\[\therefore \] The sum of smallest and largest prime number = 2 + 7 =9.
\[\therefore \] We got the sum as 9.
So option (b) is the correct answer.

Note: Every number greater than 1 can be divided by at least one prime number. All the prime numbers are odd, except for 2 which is the only even prime number. Each composite number can be factored into prime factors and individually all of these are unique in nature.