Hi Radhika,
Your question is not clear.But still I have did some programming by considering your requiment.
Script:
<script type="text/javascript">
$(function () {
$(".chb").click(function () {
if (this.checked) {
var txtVal = $("#txt").val();
$(this).val(txtVal);
}
});
});
</script>
HTML:
<input type="text" id="txt" /><br />
<input type="checkbox" class="chb" value="10" />A<br />
<input type="checkbox" class="chb" value="20" />B<br />
<input type="checkbox" class="chb" value="30" />C<br />
<input type="checkbox" class="chb" value="40" />D<br />
<input type="checkbox" class="chb" value="50" />E<br />