The phrase "ascertained number" is correct and usable in written English.
It can be used in contexts where a specific number has been determined or established through investigation or calculation.
Example: "After conducting the survey, we arrived at the ascertained number of participants who expressed interest in the event."
Alternatives: "determined number" or "established number".
While the number of cases of pandemic A/H1N1 in England was small, the Health Protection Agency ascertained numbers from laboratory testing of all known suspected cases.
§Approximated for participants in Still Working as we were unable to ascertain number of drinks per time period because of way alcohol intake was determined in baseline questionnaire.
A researcher contacted schools to ascertain numbers of eligible participants.
Questions 10-12, answered by all respondents, asked whether they would like to return their PDA to the School in addition to ascertaining numbers of students with smartphones and feedback on future directions for the project.
To determine whether these conserved genes appeared with low redundancy, we ascertained the number of paralogs in the insect-specific genes with the number of paralogs in the eukaryote/opisthokont core genes.
Looking at a Web site with friends, he checked into the possibility of asking for No. 16 -- and ascertained that number was retired in honor of Whitey Ford.
We ascertained the number and diversity of imported DENV serotypes from infected travelers during 2002 2010 (Table 3).
We also ascertained the number of years each stretch of line was in use between 1966 and 1987 (Wignall, 1983; Baker, 1990).
The tool also ascertained the number and types of staff working in the ART clinic, and how much time they spend there.
Network analysis in a Geographic Information System (GIS) ascertained the number, minimum and median distances to food outlets within 400 m and 800 m of the school location.
