2. Find all prime numbers $p$ for which $p+28$ and $p+56$ are also prime numbers.
IV/2. When dividing the number 28 by 3, we get a remainder of 1, and when dividing the number 56 by 3, we get a remainder of 2. This means that the prime number $p$ must not have a remainder of 1 or 2 when divided by 3, as otherwise, one of the numbers $p+28$ or $p+56$ would be divisible by 3. The only prime number that is divisible by 3 and that comes into consideration is the prime number 3, in which case $p+28=31$ and $p+56=59$ are indeed prime numbers.

Observation that it is important to consider remainders when dividing by 3: 3 points. Conclusion that the sought prime number is equal to $p=3: \mathbf{3}$ points. Verification that $p+28$ and $p+56$ are indeed prime numbers: 1 point.