Write the 20 numbers 1, 2, 3...20 in a row, and add 5 adjacent numbers, how many different sums can be obtained in total?
将1，2，3…20这20个数写成一行，用相邻的5个数相加，一共可以得到多少个不同的和．
<gadget id="calculator">20 - 5</gadget>
<output>15</output>

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

<result>16</result>