Целочисленная арифметика

ost = x%10;

#include <iostream>
 
class Prime
{
 
    char sym[16];
    char amount;
    int numba;
 
    void update();
 
public:
 
    void performSwap();
 
    Prime(int numba);
    ~Prime() {};
 
    operator int() {return this->numba;}
};
 
Prime::Prime(int _numba) : numba(_numba)
{
    int decs = 1;
    int temp = _numba;
    this->amount = 0;
 
    while(temp > 0)
    {
        temp /= 10;
        decs *= 10;
 
        this->sym[this->amount] = (_numba - temp * decs) / (decs / 10) ;
        ++ this->amount;
    }
}
 
void Prime::update()
{
    int decs = 1;
    int numba = 0;
 
    for(int i = 0 ; i < this->amount ;++i)
    {
        numba += int(this->sym[i]) * decs;
        decs *= 10;
    }
 
    this->numba = numba;
}
 
void Prime::performSwap()
{
    char t;
    t = sym[0];
    sym[0] = sym[this->amount - 1];
    sym[this->amount - 1] = t;
 
    this->update();
}
 
int main(int,char**)
{
Prime a(123456789);
a.performSwap();
 
std::cout << int(a);
 
std::cin.ignore();
 
return 0;
}