library - sqrt

[t4sk]

replace library math example with square root function

[t4sk]

  function sqrt(uint y) internal pure returns (uint z) {
    if (y > 3) {
      z = y;
      uint x = y / 2 + 1;
      while (x < z) {
        z = x;
        x = (y / x + x) / 2;
      }
    } else if (y != 0) {
      z = 1;
    }
    // else z = 0 (default value)
  }