Edit in JSFiddle

<div id="parent">
   <div id="child">Estoy flotando</div>
  Texto dummy aqui
   <span class="clearfix"></span>
</div>
<br />
<div id="parent2">
   <div id="child2">Estoy flotando 2</div>
  Texto dummy aqui 2
</div>

<br />
<div id="parent3">
   <div id="child3">Estoy flotando 3</div>
  Texto dummy aqui 3
</div>

/************primer metodo***************/
#parent {
 width:200px;
 background-color:rgb(167, 205, 240);
 padding:5px;
}

#child { 
    float:right; width:75px; 
    background-color:rgb(125, 199, 131);
    color:white; 
    height:100px;
    padding:5px; 
}

.clearfix { 
    display:block;
    clear:both;
    width:0px;
    height:0px; 
}
/**********segundo metodo*******************/
#parent2 {
 width:200px;
 background-color:rgb(167, 205, 240);
 padding:5px;
}
 #parent2:after { 
    content:"";
    display:block;
    clear:both; 
    visibility:hidden; 
}

#child2 { 
    float:right; width:75px; 
    background-color:rgb(125, 199, 131);
    color:white; 
    height:100px;
    padding:5px; 
}
/***********tercer metodo************************/


#parent3 {
   overflow:hidden;
 width:200px;
 background-color:rgb(167, 205, 240);
 padding:5px;
}

#child3 { 
    float:right; width:75px; 
    background-color:rgb(125, 199, 131);
    color:white; 
    height:100px;
    padding:5px; 
}