a simple javascript calculator
<div class="calculator">
<input type="text" class="calculator-screen" value="" disabled />
<div class="calculator-keys">
<button type="button" class="operator" value="+">+</button>
<button type="button" class="operator" value="-">-</button>
<button type="button" class="operator" value="*">×</button>
<button type="button" class="operator" value="/">÷</button>
<button type="button" value="7">7</button>
<button type="button" value="8">8</button>
<button type="button" value="9">9</button>
<button type="button" value="4">4</button>
<button type="button" value="5">5</button>
<button type="button" value="6">6</button>
<button type="button" value="1">1</button>
<button type="button" value="2">2</button>
<button type="button" value="3">3</button>
<button type="button" value="0">0</button>
<button type="button" class="decimal" value=".">.</button>
<button type="button" class="all-clear" value="all-clear">AC</button>
<button type="button" class="equal-sign operator" value="=">=</button>
</div>
</div>