[URL]https://ideone.com/xUy8OW[/URL]

<div id="s" />
<form action="#" method="POST">
<p>Sayı 1</p><input type="number" name="s1" required="" /><br />
<p>Sayı 2</p><input type="number" name="s2" required="" />
<p><input type="submit" name="topla" value="Topla" /></p>
<p><input type="submit" name="carp" value="Çarp" /></p>
<p><input type="submit" name="bol" value="Bölme" /></p>
<p><input type="submit" name="cikart" value="Çıkartma" /></p>
</form>

<?php
    
function topla($s1,$s2)
{
    if ($_POST)
    {
        $sayi1=$_POST['s1'];
        $sayi2=$_POST['s2'];
        $sonuc = $sayi1 + $sayi2;
        echo "Çıkan Sonuç($sayi1+$sayi2) = " . $sonuc;
    }
}

function carp($c1,$c2)
{
    if ($_POST)
    {
        $carp1=$_POST['s1'];
        $carp2=$_POST['s2'];
        $carpim = $carp1 * $carp2;
        echo "Çıkan Sonuç($carp1*$carp2) = " . $carpim;
    }
}

function bolme($bol1,$bol2)
{
    if ($_POST)
    {
        $bol1=$_POST['s1'];
        $bol2=$_POST['s2'];
        $bolum = $bol1 / $bol2;
        echo "Çıkan Sonuç($bol1/$bol2) = " . $bolum;
    }
}

function cikartma($c1,$c2)
{
    if ($_POST)
    {
        $c1=$_POST['s1'];
        $c2=$_POST['s2'];
        $cikart = $c1 - $c2;
        echo "Çıkan Sonuç($c1-$c2) = " . $cikart;
    }
}


topla(1,1);
echo "<br>.<br>";
carp(1,1);
echo "<br>.<br>";
bolme(1,1);
echo "<br>.<br>";
cikartma(1,1);

?>