<div id="Coalcounter"></div>
<div id="CoalRatecounter"></div>
<button id="Coalbutton" onclick="addCoal()">Mine</button>
<button id="CoalClicker" onclick="addCoalClicker()">Coal Clicker</button>
<button id="CoalRate" onclick="addCoalRate()">Coal Rate</button>
<div id="alerts">
<div id="errors"></div>
</div>

var Coal=0;
var CoalClicker=1;
var CoalClickerPrice=50;
var CoalRate=0;
var CoalRatePrice=50;

<script>
    function addCoal(){
    Coal+=CoalClicker;
    totalCoal+=CoalClicker;
    document.getElementById("Coalcounter").innerHTML="Coal : " + Math.round(Coal);
    document.getElementById("CoalClickercost").innerHTML="Upgrade Coal Clicker : " + Math.round(CoalClickerPrice);
    document.getElementById("CoalRatecost").innerHTML="Upgrade Coal Rate : " + Math.round(CoalRatePrice);
    }
    document.getElementById("Coalcounter").innerHTML="Coal : " + Math.round(Coal);
    document.getElementById("CoalClickercost").innerHTML="Upgrade Coal Clicker : " + Math.round(CoalClickerPrice);
    document.getElementById("CoalRatecost").innerHTML="Upgrade Coal Rate : " + Math.round(CoalRatePrice);
</script>
<script>
    var increment = setInterval(increment,1000); // gain 1 ever second // THIS IS WHAT I WANT TO CHANGE
    function increment(){
    Coal = Coal % 99999999999999999999 + CoalRate;
    totalCoal = totalCoal % 99999999999999999999 + CoalRate;
    document.getElementById("Coalcounter").innerHTML="Coal : " + Math.round(Coal);
    document.getElementById("CoalClickercost").innerHTML="Upgrade Coal Clicker : " + Math.round(CoalClickerPrice);
    document.getElementById("CoalRatecost").innerHTML="Upgrade Coal Rate : " + Math.round(CoalRatePrice);
    }
</script>
<script>
    var increment = setInterval(increment,5000);
    function increment(){
    document.getElementById("errors").innerHTML="";
    }
</script>
<Script>
    var CoalClicker=1;
    function addCoalClicker(){
    if(Coal>CoalClickerPrice-1){
    CoalClicker+=1;
    Coal-=CoalClickerPrice;
    CoalClickerPrice*=1.2;
    document.getElementById("Coalcounter").innerHTML="Coal : " + Math.round(Coal);
    document.getElementById("CoalClickercost").innerHTML="Upgrade Coal Clicker : " + Math.round(CoalClickerPrice);
    document.getElementById("CoalRatecost").innerHTML="Upgrade Coal Rate : " + Math.round(CoalRatePrice);
    }
    else
    {
    document.getElementById("errors").innerHTML="Not Enough Coal!"; // Note
    }
    }
</script>
<Script>
    var CoalRate=0;
    function addCoalRate(){
    if(Coal>CoalRatePrice-1){
    CoalRate+=1;
    Coal-=CoalRatePrice;
    CoalRatePrice*=1.2;
    document.getElementById("Coalcounter").innerHTML="Coal : " + Math.round(Coal);
    document.getElementById("CoalClickercost").innerHTML="Upgrade Coal Clicker : " + Math.round(CoalClickerPrice);
    document.getElementById("CoalRatecost").innerHTML="Upgrade Coal Rate : " + Math.round(CoalRatePrice);
    }
    else
    {
    document.getElementById("errors").innerHTML="Not Enough Coal!"; // Note
    }
    }
</script>