Multiplication table.

#include <iostream>
#include <iomanip>
#include <string>

int main() {
  std::cout << "print out multiplication table\n";
  std::cout << std::string(80, '-') << '\n';

  auto constexpr max { 20u };
  auto val { 0u };
  std::cout << "number from 1 to " << max << ": ";
  std::cin >> val;
  std::cout.put('\n');
  if (val > 0u && val <= 20u) {
    for (auto nr { 1u }; nr <= max; ++nr) {
      std::cout << std::setw(3) << nr
                << " x"
                << std::setw(3) << val
                << " ="
                << std::setw(4) << nr * val
                << '\n';
    }
    std::cout << std::endl;
  }
  else {
    std::cout << val << " out of range!\n";
  }

  return 0;
}