From A to B, you can take a train, a ship, or an airplane. In one day, there are 4 trains, 2 ships and 1 plane from A to B. Then how many different ways of walking from A to B by these means of transportation in one day?
从甲地到乙地，可以乘火车，也可乘轮船，还可以乘飞机．在一天中，从甲地到乙有4班火车，2班轮船，1班飞机．那么在一天中乘坐这些交通工具从甲地到乙地，共有多少种不同的走法．
<gadget id="calculator">4 + 2 + 1</gadget>
<output>7</output>

<result>7</result>