<div class="item" value="800"></div>
<div class="item" value="801"></div>
<div class="item" value="802"></div>
<div class="item" value="803"></div>
var Vallue = $('#item_answer').attr("value");
$('.item'+Vallue+'').hide();
<div class="item" data-value="800"></div>
<div class="item" data-value="801"></div>
<div class="item800"></div>
<div class="item801"></div>
$(".item").each(function(){
var num = this.dataset.value;
$('.item'+num).hide();
});