A prime number times another prime number is?

Answer 1

If you multiply two prime numbers, the product (result) will be a composite number, not a Prime number. A prime number has exactly two factors, 1 and itself. The product of two prime numbers will have those two numbers as factors, as well.

The sum of two prime numbers might be prime if one of those two numbers is 2, the only even prime number, but otherwise it will not be a prime because two odd numbers will have an even sum, which means it is divisible by 2.

Examples:

2 + 3 = 5 (prime)

3 + 7 = 10 (not prime)

13 + 17 = 30 (not prime)

If you multiply two prime numbers, the sum of the digits of the product might or might not be prime.

Examples:

2 x 7 = 14, sum of digits is 5 (prime)

2 x 11 = 22, sum of digits is 4 (not prime)

3 x 5 = 15, sum of digits is 6 (not prime)

3 x 7 = 21, sum of digits is 3 (prime)

5 x 7 = 35, sum of digits is 8 (prime)