Did you know that the Russian expressions ни разу and не раз have opposite meanings, although they seem very similar? Ни разу means “never, not once”, it is a synonym of никогда (never). However, не раз means “more than once”.
- Я ни разу не был в Греции. I have never been to Greece.
- Я не раз видела этого человека в метро. I have seen this person many times (more than once) in the metro.