<div id="calc-history">
    <span>История</span>
    <ol id="calc-history-list"></ol>
</div>

<script>
   var calculator  = {
        resultsId: 'btnDivide',
        resultsValue: '0',
        memoryValue: '',
        historyId: 'calc-history-list',
        historyValue: []
   }

   //addToHistory:

   function () {
        if (isNaN(this.resultsValue) === false) {
            var div = document.createElement('li'), tag = document.getElementById(this.historyId);
            div.innerHTML = this.memoryValue + ' = ' + this.resultsValue;
            tag.insertBefore(div, tag.firstChild);
        }
    }

    //clearHistory:

    function () {
        $('#' + this.historyId + '> li').remove();
    }
</script>