What is the fax number for the district with the most number of crimes in January, 2018?
fax number refers to fax; the most number of crimes refers to max(count(case_number)); in January 2018 refers to date like '%1/2018%'
SELECT T1.fax FROM District AS T1 INNER JOIN Crime AS T2 ON T1.district_no = T2.district_no WHERE T2.date LIKE '%1/2018%' GROUP BY T2.district_no ORDER BY COUNT(case_number) DESC LIMIT 1