1. Prím

#include <iostream>

using namespace std;

int main()
{
    bool prim = true;
    int szam;
    cin >> szam;
    for(int oszto = 2; oszto <= szam/2; oszto++){
        if (szam % oszto == 0){
            prim = false;
        }
    }
    if (prim) {
        cout << "a szam prim";
    } else {
        cout << "a szam nem prim";
    }
    return 0;
}

2. Pallindróm

#include <iostream>

using namespace std;

int main()
{
    int szam, ujszam = 0, temp;
    cin >> szam;
    temp = szam;
    while (temp > 0) {
        int szamjegy = temp % 10;
        temp = temp / 10;
        ujszam = ujszam * 10 + szamjegy;
    }
    if (ujszam == szam) {
        cout << "pallindrom";
    } else {
        cout << "nem pallindrom";
    }

    return 0;
}

3. Fibbonacci

#include <iostream>

using namespace std;

int main()
{
    int prev=1, next=1, F=1, n;
    cin >> n;
    for(int i = 3; i<= n; i++)
    {
        F = prev + next;
        prev = next;
        next = F;
    }
    cout << F;
    return 0;
}

4. Lnko/Lkkt

#include <iostream>

using namespace std;

int main()
{
    int a, b, lkkt;
    cin >> a >> b;
    lkkt = a * b;
    while(a != b){
        if (a>b){
            a -= b;
        } else {
            b -= a;
        }
    }
    cout << "lnko " << a << endl;
    cout << "lkkt " << lkkt / a;
    return 0;
}