Szeto 23/4/2024
<style>
    input { text-align:center; color:red; }
</style>
<p>
<script>
function add_ab(){
    let a= Number(document.all.numA.value);
    let b= Number(document.all.numB.value);
    document.all.ans.value = a+b;
}

function sub_ab(){
    let a= Number(document.all.numA.value);
    let b= Number(document.all.numB.value);
    document.all.ans.value = a-b;
}

function mul_ab(){
    let a= Number(document.all.numA.value);
    let b= Number(document.all.numB.value);
    document.all.ans.value = a*b;
}

function random_numbers(){
    document.all.numA.value = 10*Math.ceil(Math.random()*10);
    document.all.numB.value = 10*(Math.floor(Math.random()*10)+1);
}

function change_b(){
    document.all.numB.value = document.all.numC.value;
}
</script>

A: <input type="number" name="numA" size="5" value="10">
B: <input type="number" name="numB" size="5" value="50">
C: <input type="range" name="numC" value="30"
 min="0" max="100" onmousemove="change_b();">

<p>
<input type="button" value="A+B" onclick="add_ab();">
<input type="button" value="A-B" onclick="sub_ab();">
<input type="button" value="AxB" onclick="mul_ab();">
<input type="button" value="random" onclick="random_numbers();">
<p>
Answer: <input type="text" name="ans" size="10" value="">