The sum of the upper, lower, left and right numbers on Xiaoming's birthday on the calendar is 60, so what is the date of Xiaoming's birthday in this month.
月历上小明生日那天的上、下、左、右四个日期数的和是60，那么小明的生日是这个月的多少号．
<gadget id="calculator">60 - 1 - 7</gadget>
<output>52</output>

<gadget id="calculator">1 + 7 + 52</gadget>
<output>60</output>

<gadget id="calculator">1 + 1 + 1 + 1</gadget>
<output>4</output>

<gadget id="calculator">60 / 4</gadget>
<output>15</output>

<result>15</result>