I changed the logic of your script a little bit, working with name to take the elements that are part of your set, and assigning a data-* to store the value of div.
Solution 1:
var inputvar = document.getElementById("numerodemqs_input"),
number_mqs = document.getElementById("resultado1");
inputvar.addEventListener("input", function() {
  number_mqs.innerHTML = inputvar.value;
  /* Linha 1 */ var elementos = document.getElementsByName("div");
  /* Linha 2 */ for (i = 0; i < elementos.length; i++) {
    /* Linha 3 */ value_element = elementos[i].getAttribute('data-value');
    /* Linha 4 */ if (value_element == inputvar.value) {
      displayBlock(elementos[i]);
    } else {
      displayNone(elementos[i]);
    }
  }
}, false);
/* Para deixar algo invisível */
function displayNone(element) {
    element.style.display = "none";
  }
  /* Para deixar algo visível */
function displayBlock(element) {
  element.style.display = "block";
}
<h4>Quantas Media Queries o Header Estático possui?</h4>
<input id="numerodemqs_input" type="range" min="1" max="5" value="">
<h5 id="resultado1"></h5>
<div name="div" data-value="1">
  <h4>Este é para o 1.</h4>
</div>
<div name="div" data-value="2">
  <h4>Este é para o 2.</h4>
</div>
<div name="div" data-value="3">
  <h4>Este é para o 3.</h4>
</div>
<div name="div" data-value="4">
  <h4>Este é para o 4.</h4>
</div>
<div name="div" data-value="5">
  <h4>Este é para o 5.</h4>
</div>
 
 
Explanation of the above code:
Line 1: I take all the elements* inside the form they have
  determined name that I set, in case div, and play within a
  array;
Line 2: Executing a for to iterate on top of each element inside
  of array, elementos.length tells me the amount of elements that the
  array possesses;
Line 3: I take the value inside the attribute data-value of
  element;
Row 4: I check the element value input is the same value as
  current gap element, if it is, is why the element should be displayed,
  then I send his reference to your function, if it’s not, it’s because
  should not be displayed;
*Note: I’m taking the element reference, not the id, or other attribute, so it is easier to change it if it is
  necessary.
Remembering the attributes of the type data-* are a new implementation of html5, then for some older browsers, or mobile devices may not have support, see a more complete list here, maybe a better solution (cross-browsing) was a mix of what was done, only catching the id of the elements by the attribute name and with the id whether or not to block the view.
Solution 2:
var inputvar = document.getElementById("numerodemqs_input"),
number_mqs = document.getElementById("resultado1");
inputvar.addEventListener("input", function() {
  number_mqs.innerHTML = inputvar.value;
  var elementos = document.getElementsByName("div");
  for (i = 0; i < elementos.length; i++) {
    value_element = elementos[i].getAttribute('id');
    if (value_element == inputvar.value) {
      displayBlock(elementos[i]);
    } else {
      displayNone(elementos[i]);
    }
  }
}, false);
/* Para deixar algo invisível */
function displayNone(element) {
    element.style.display = "none";
  }
  /* Para deixar algo visível */
function displayBlock(element) {
  element.style.display = "block";
}
<h4>Quantas Media Queries o Header Estático possui?</h4>
<input id="numerodemqs_input" type="range" min="1" max="5" value="">
<h5 id="resultado1"></h5>
<div id="1" name="div">
  <h4>Este é para o 1.</h4>
</div>
<div id="2" name="div">
  <h4>Este é para o 2.</h4>
</div>
<div id="3" name="div">
  <h4>Este é para o 3.</h4>
</div>
<div id="4" name="div">
  <h4>Este é para o 4.</h4>
</div>
<div id="5" name="div">
  <h4>Este é para o 5.</h4>
</div>
 
 
Explanation of the above code:
The code is similar to the previous one except for the attribute you use to reference the correct element, instead of using an attribute of type data-*, I use the id.
							
							
						 
Thank you very much Thank you Very much! You saved a lot, haha Would you be able to explain a little that elements.length? Thanks a lot
– Giancarlo Soldera Graziano
the attribute
nameserves to locate anchors, the right attribute to be used in this case would be aclassfollowed byquerySelectorAll()(orgetElementsByClassName().– MoshMage
@Moshmage note that in my example I use the
nameonly to locate and take the reference of the elements that I will work, there is no standard for how to work in these cases :)– MarceloBoni