1:<input   type="text" value=""  id="t1"   /> <br/>
2:<input   type="text"  value="" id="t2"   /> <br/>
3:<input   type="text" value=""  id="t3"   /> <br/>
4:<input   type="text" value=""  id="t4"   /> <br/>
<input type="button" onclick="Check()" value="提交"/>
<script >
    var $ = function (el) {
        return (typeof el == 'object')?el:document.getElementById(el);
    };
    var Check=function(){        
         v1=$("t1").value;
         v2=$("t2").value;
         v3=$("t3").value;
         v4=$("t4").value;        
        if(v2/v1==2 && v3/v1==3 && v4/v1==4)
        {
            alert("成功！");
        }
        else
        {
            alert("失败！");
        }

    };
</script>

------解决方案--------------------
HTML code

<input   type="text"   name="t1"   /> 
<input   type="text"   name="t2"   /> 
<input   type="text"   name="t3"   /> 
<input   type="text"   name="t4"   /> 

<input type="button" value="check" onclick="check()" />
<script>
    var check = function(){
        var objs = new Array(t1 ,t2 ,t3 ,t4);
        for(var i=0;i<objs.length;i++)
        {
            if(objs[i].value == "")
            {
                alert("input "+ (i+1) +" is null");
                break;
            }
            if(isNaN(objs[i].value/1))
            {
                alert("input "+ (i+1) +" is not bumber!");
                break;
            }
        }
        if((objs[0].value*1 + objs[3].value*1) != (objs[1].value*1 + objs[2].value*1))
        {
            alert("is not rule");
        }
    };
</script>