Untitled

<html>
  <head>
    <title>Calcolatrice</title>
  	<link rel="stylesheet" type="text/css" media="all" href="calcolatrice.css" />
  </head>
  <body>
    <div class="calc">
    <input  class="d" type="text" id="testo" name="display"><br>
    <div class="segni">
    <button onclick="document.getElementById('testo').value+='+'">+</button>
    <button onclick="document.getElementById('testo').value+='-'">-</button>
    <button onclick="document.getElementById('testo').value+='*'">*</button>
    <button onclick="document.getElementById('testo').value+='/'">/</button><br>
    </div>

    <div class="789">
    <button onclick="document.getElementById('testo').value+='7'">7</button>
    <button onclick="document.getElementById('testo').value+='8'">8</button>
    <button onclick="document.getElementById('testo').value+='9'">9</button>
    <button id="btn" class="uguale" onclick="document.getElementById('testo').value=eval(document.getElementById('testo').value)">=</button>

    <br>
    </div>

    <div class="456">
    <button onclick="document.getElementById('testo').value+='4'">4</button>
    <button onclick="document.getElementById('testo').value+='5'">5</button>
    <button onclick="document.getElementById('testo').value+='6'">6</button><br>
    </div>

    <div class="123">
    <button onclick="document.getElementById('testo').value+='1'">1</button>
    <button onclick="document.getElementById('testo').value+='2'">2</button>
    <button onclick="document.getElementById('testo').value+='3'">3</button><br>
    </div>
    <div class="zero">
    <button onclick="document.getElementById('testo').value+='0'">0</button>
    <button onclick="document.getElementById('testo').value+='.'">.</button>
    <button class="AC" onclick="document.getElementById('testo').value=''">AC</button><br>
</div>
</div>
</body>
</html>