<script type="text/javascript">
function getOptions()
{
var x=document.getElementById("cuotas").value;
if(x==1){
document.getElementById('unoo').style.display='blo ck';
document.getElementById('uno').style.visibility = 'visible';
}
}
function soloNumeros(evt) {
var tecla = String.fromCharCode(evt.which || evt.keyCode);
if ( !/[\d.\b\r]/.test(tecla) ) return false;
return true;
}
</script>
</head>
<body>
<form>
Seleccione el numero de cuotas:
<select id="cuotas">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
<option>6</option>
</select>
<div id="uno" style="visibility:hidden">
<input type="text" id="unoo" maxlength="10" onkeypress="return soloNumeros(event);" class="text ui-widget-content ui-corner-all" style="display: none;"/>
<input type="text" name="fecha_terminacion1" id="fecha_terminacion1" class="text ui-widget-content ui-corner-all" />
</div>
<br /><br />
<input type="button" onclick="getOptions()" value="Output all options">
</form>
</body>
</html>