You never said what language to use so here is your answer in Javascript:
<script type="text/javascript">
function checkPal() {
var reversestr = "";
var str = window.prompt("Enter a 3 digit number: ");
var i = str.length;
for(var j=i; j>=0; j--) {
reversestr = reversestr+str.charAt(j);
}
if(str == reversestr) {
alert(str+" Is Palindrome");
}
else {
alert(str+" Is not a Palindrome");
}
}
checkPal();
</script>
