Code:
<script>
function increaseValue(strid,p,pr) {
var v = parseInt(strid.value);
v= isNaN(v) ? 0 : v;
v++;
strid.value = v;
var total=v*p;
pr.value=total;
}
function decreaseValue(strid,p,pr) {
var v = parseInt(strid.value);
v = isNaN(v)