Uncle Wang went to the lottery station to buy sports lottery tickets. He wanted to buy 5 lottery tickets with consecutive numbers in a group of 20 lottery tickets with serial numbers ending in 01 to 20. How many different choices did he have?
王叔叔到彩票站买体育彩票，他想在一组尾号01到20的20张连号彩票中买5张连号彩票，他一共有多少种不同的选择．
<gadget id="calculator">20 - 5</gadget>
<output>15</output>

<gadget id="calculator">15 + 1</gadget>
<output>16</output>

<result>16</result>