The six words "Learning to change fate" need to be written in 6 different colors. Now there are only 6 different colors of pens. How many different ways of writing are there?
"学习改变命运"这六个字要用6种不同颜色来写，现只有6种不同颜色的笔，问共有多少种不同的写法？
<gadget id="calculator">6 * 5 * 4 * 3 * 2 * 1</gadget>
<output>720</output>

<result>720</result>