Answer: Positioning of the Number
The number must always be included before the period, never after, and must ideally appear at the end of your statement.
Here is an example :
“The international comparisons present the main statistical indicators of more than 230 countries and territories, grouped by theme: population and income, labour force and prices, gross domestic product, international trade and investments, education and communication, health”1.
1 Institut de la statistique, Gouvernement du Québec. December 3, 2003. <http://www.stat.gouv.qc.ca/donstat/econm_finnc/conjn_econm/compr_inter/index_an.htm>.