ascertain

verb

1. 1

   be careful or certain to do something; make certain of something

   He verified that the valves were closed

   See that the curtains are closed

2. 2

   learn or discover with certainty

3. 3

   establish after a calculation, investigation, experiment, survey, or study

   find the product of two numbers

   The physicist who found the elusive particle won the Nobel Prize

4. 4

   find out, learn, or determine with certainty, usually by making an inquiry or other effort

   I want to see whether she speaks French

   See whether it works