Analysis of information sources in references of the Wikipedia article "42 (number)" in English language version.
It is the custom to have no fewer than 48 lines, representing the journeys of Israel, and some say no fewer than 42, because of what God did in the Sinai wilderness at Kadesh. Also, we don't have more than 60 lines, representing the 60 myriads of Israel who received the Torah.
(At the present day the forty-two-lined column is the generally accepted style of the scroll, its length being about 24 inches.)