Certain – certaine (f), certain (m)
(used as in: A certain amount)
(Pronounced ser-ten (f) ser-tan (m))
To remember that Certain is pronounced ser-ten or ser-tan (certaine or certain) in French, use the following mnemonic:
Certain people will certainly (certain) get serious tan (certain) lines in the sun.

Examples of certaine or certain (certain) in a sentence
Certains projets sont faciles.
(Certain projects are easy.)
Cela prend un certain temps.
(That takes a certain amount of time.)
Un certain nombre de personnes est venu.
(A certain number of people came.)