There are 4 ways to go from home to school, and 3 ways to go from school to gymnasium, so how many different ways are there to go from home to library through school?
从家地到学校地有4条路可走，从学校地到体育馆有3条路可走，那么从家经过学校到图书馆共有多少种不同的走法．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>