JQuery selection optimization
<p>I have a JQuery validation files that look as follow:</p>

<pre><code>$('#TextBoxRisultati2b').on('blur', function () {
    var $this = $('#TextBoxRisultati2b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati6b').on('blur', function () {
    var $this = $('#TextBoxRisultati6b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati10b').on('blur', function () {
    var $this = $('#TextBoxRisultati10b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati14b').on('blur', function () {
    var $this = $('#TextBoxRisultati14b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati18b').on('blur', function () {
    var $this = $('#TextBoxRisultati18b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati22b').on('blur', function () {
    var $this = $('#TextBoxRisultati22b');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati4').on('blur', function () {
    var $this = $('#TextBoxRisultati4');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati8').on('blur', function () {
    var $this = $('#TextBoxRisultati8');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati12').on('blur', function () {
    var $this = $('#TextBoxRisultati12');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati16').on('blur', function () {
    var $this = $('#TextBoxRisultati16');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati20').on('blur', function () {
    var $this = $('#TextBoxRisultati20');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxRisultati24').on('blur', function () {
    var $this = $('#TextBoxRisultati24');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxObiettivi3').on('blur', function () {
    var $this = $('#TextBoxObiettivi3');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxObiettivi6').on('blur', function () {
    var $this = $('#TextBoxObiettivi6');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxObiettivi9').on('blur', function () {
    var $this = $('#TextBoxObiettivi9');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});
$('#TextBoxObiettivi12').on('blur', function () {
    var $this = $('#TextBoxObiettivi12');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxObiettivi15').on('blur', function () {
    var $this = $('#TextBoxObiettivi15');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});

$('#TextBoxObiettivi18').on('blur', function () {
    var $this = $('#TextBoxObiettivi18');
    if ($this.val() == '' || $this.val() === undefined) $this.val('0');
});
</code></pre>

<p>The selection are all the same. The entire validation file is very verbose. Is there a way to optimize this code?</p>
