test.html

<!DOCTYPE html>
<html>
<body>

<button onclick="func()">Generate number</button>
<p id="para">hello</p>

<script>
	var s1 = 12345; // 1000 * Math.random();
    var s2 = 67890; // 1000 * Math.random();
    var s3 = 98765; // 1000 * Math.random();

	var text = "";
    var interval = {start:0, end:10};
    var prev = [];

    var total = 0;
    for (let i = 0; i < 100000; i++) {
        total += random();
    }
    console.log(total / 100000);
    
	function func() {
    	number = random();
        prev.push(number);
        text += number.toString() + "<br>";
        document.getElementById("para").innerHTML = text;
        let avrg = 0;
        for (let num of prev) {
            avrg += num;
        }
        avrg /= prev.length;
        console.log(avrg);
    }
    
    function random() {
    	var Z, k;
		k = Math.floor(s1 / 206);
        s1 = 157 * (s1 - (k * 206)) - (k * 21);
        if (s1 < 0) {s1 += 32363};
        
        k = Math.floor(s2 / 217);
        s2 = 146 * (s2 - (k * 217)) - (k * 45);
        if (s2 < 0) {s2 += 31727};
        
        k = Math.floor(s3 / 222);
        s3 = 142 * (s3 - (k * 222)) - (k * 133);
        if (s3 < 0) {s3 += 31657};
        
        Z = s1 - s2;
        if (Z > 706) {Z -= 32362};
        Z += s3;
        if (Z < 1) {Z += 32362};
        
        //return Z * 3.0899 / 100000;
        //return Math.floor(Z / 3236);
        return Math.floor(Z / 2942);
    }
</script>

</body>
</html>