JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" value="10" id="text">

<input type="radio" id="check" value="101" onClick="count(a2=this.value);" name="check">
<label for="check">101</label>
<input type="radio" id="check2" value="11" onClick="count(a2=this.value);" name="check">
<label for="check2">11</label>

<input type="text" value="" id="end">
<script>
function count(){
    var a1=document.getElementById('text').value;
document.getElementById('end').value = a1*a2;
    }
</script>

CSS

#end {border-width: 0px;
color: red;
}