I had fun creating it, it is not perfect and you will need some tweaking to get it exacly like the image but it should get you on the right path :
html:
<div id="abi">ABI</div>
<div id="number">12/19</div>
CSS
div{
float:left;
height:60px;
line-height:60px;
font-size:20px;
margin:0;
padding:0;
}
#abi{
width:75px;
background:gray;
color:blue;
padding-left:25px;
position:relative;
z-index:2;
-webkit-border-radius: 5px 0 0 5px;
border-radius: 5px 0 0 5px;
}
#abi:after{
content:"";
position:absolute;
right:-10px;
top: 19px;
width: 0;
height: 0;
border-top: 11px solid transparent;
border-bottom: 10px solid transparent;
border-left: 10px solid gray;
}
#number{
width:155px;
text-align:right;
padding-right:25px;
background:blue;
color:gray;
-webkit-border-radius: 0 5px 5px 0;
border-radius: 0 5px 5px 0;
}