Choose 2 numbers from 1, 3, 5, and choose 2 numbers from 2, 4, 6. How many four-digit numbers can be formed without repeating numbers?
从1、3、5中任选2个数字，从2、4、6中任选2个数字，共可组成多少个没有重复数字的四位数？
<gadget id="calculator">3 * 3 * 4 * 3 * 2 * 1</gadget>
<output>216</output>

<result>216</result>