<p>1) Can you tell me how to say ! ?
2) What are the differences in use between them?</p>
<ol>
<li>factorial</li>
<li>permutation means that order is taken into consideration, and is calculated P(N,X)= N!/(N-X)!</li>
</ol>
<p>combinations means that order does not matter, and is calculated C(N,X)=N!/[(N-X)! * X!] </p>
<p>factorial is just N!= N * (N-1) * (N-2).....* 2 * 1 for example: 10!=10<em>9</em>8<em>7</em>6<em>5</em>4<em>3</em>2*1</p>
<p>if you're really interested then you should go to a local library and rent a book about permutations and combinations-----counting in general.</p>