There are 1 yellow, red, green, basket, purple, and orange signal flags each. From the 6 signal flags of different colors, one or two signal flags of different colors are taken out each time as a signal. How many different approaches are there?
有黄、红、绿、篮、紫、橙色的信号旗各1面．从这6种不同颜色的信号旗中，每次取出1面或者2面不同颜色的信号旗作为一种信号．共有多少种不同的取法？
<gadget id="calculator">6 + 15</gadget>
<output>21</output>

<result>21</result>