handleSubmit = (event) => {
  event.preventDefault();
  this.props.history.replace({
    pathname: "/result",
    state: {
      value:
        "Your saving range is: $" +
        Math.floor(1.69 * this.state.square * (10 / 100)) +
        "- $" +
        Math.floor(1.69 * this.state.square * (30 / 100))
    }
  });
};

class Result extends Component {
  render() {
    return (
      

        
You could save between
        
{this.props.location.state.value}
 // <-- route state
        Use Calculator Again
      
    );
  }
}