Around how many animals have gone extinct?

Extinction of animals (or rather species) happens all the time and has been going on for hundreds of millions of years. All the fossils we find in the rocks are species that are now extinct. It is therefore impossible to tell you just how many animals have gone extinct.

However, you question may have been prompted by concerns for our planet and its ecosystem today and you may therefore be asking

How many animals have gone extinct because of man's activities?

This a good question, unfortunately I don't know the answer to this so I will ask it.

(The answer is in the related question below)