sandy wrote:

viki69 wrote:

but why is it not specified in the question what does it want, if not specified to multiply the primes, i can just add them which is<1155, then the ans must be D, cannot be determined

A number formed by adding prime number do not have the same prime as factors.

Example 2 and 3 are prime numbers; 6 or 2 * 3 has prime factors 2 and 3.

But 2+ 3= 5 which doe snot have prime factors as 2 and/or 3.

So u mean to say that whenever factors are talked about, we have to consider multiplication and noting else, but there are other cases too, for example, 3+7=10=2*5 all are prime of 10

I apologise if you get frustated because of my reasoning, but please help me understand this concept. Thanks in advance.