<script>

    function changeSize(number) {

        document.getElementById("10").style.fontSize = number;

        document.getElementById("20").style.fontSize = number;

        document.getElementById("30").style.fontSize = number;

        document.getElementById("40").style.fontSize = number;

        document.getElementById("50").style.fontSize = number;

    }

    </script>

@{

​

    int[] numbers = new int[]{10,20,30,40,50};

    foreach (int number in numbers){

        {<button id="@number" onclick="changeSize('@number')">@number</button><br></br>}

    }

}

​