Create a calculation that we can put into a web page. The UI will resemble a typical calculator were line numbers and operators are in grid. Put everything into a single html file.


    <input type="text" id="result"/>
    <input type="button" value="1" onclick="addToInput('1')"/>
    <input type="button" value="2" onclick="addToInput('2')"/>
    <input type="button" value="3" onclick="addToInput('3')"/>
    <input type="button" value="+" onclick="addToInput('+')"/>
    <input type="button" value="4" onclick="addToInput('4')"/>
    <input type="button" value="5" onclick="addToInput('5')"/>
    <input type="button" value="6" onclick="addToInput('6')"/>
    <input type="button" value="-" onclick="addToInput('-')"/>
    <input type="button" value="7" onclick="addToInput('7')"/>
    <input type="button" value="8" onclick="addToInput('8')"/>
    <input type="button" value="9" onclick="addToInput('9')"/>
    <input type="button" value="*" onclick="addToInput('*')"/>
    <input type="button" value="." onclick="addToInput('.')"/>
    <input type="button" value="0" onclick="addToInput('0')"/>
    <input type="button" value="=" onclick="calculate()"/>
    <input type="button" value="/" onclick="addToInput('/')"/>
    <input type="button" value="C" onclick="clearInput()"/>
    function addToInput(val) {
        var result = document.getElementById('result');
        result.value += val;
    function clearInput() {
        var result = document.getElementById('result');
        result.value = "";
    function calculate() {
        var result = document.getElementById('result');
        var calculation = result.value;
        var answer = eval(calculation);
        result.value = answer;