O'Zebra's family lives in an alley on a street. This alley is numbered sequentially from No. 1 to the next. If the number of O'Zebra's house is removed, the sum of the remaining household numbers is exactly 61. What is the number of O'Zema's house?
奥斑马家住在一条街的胡同里，这条胡同从1号依次往下顺次编号，如果去掉奥斑马家的编号，剩下住户编号之和恰好是61，奥斑马家住多少号．
<gadget id="calculator">91 - 61</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<result>15</result>