Edit in JSFiddle

Array.prototype.forEach.call(document.getElementsByTagName("input"), function(input){
    var letra = input.id[input.id.length - 1];
    input.addEventListener("change", function(){
        document.getElementById("salida" + letra).innerText = input.value;
    });
});

<div>
    Rango A: <label id = "salidaA">0</label>
    <input type = "range" id = "rangoA" min = 0 max = 10 value = 0 />
</div>

<div>
    Rango B: <label id = "salidaB">0</label>
    <input type = "range" id = "rangoB" min = 0 max = 10 value = 0 />
</div>