Well wonder no more, as these special extension billboards for The Expendables 3 help solve that question, and the answer is sixteen.
The smaller cast billboard was spotted along Sunset Boulevard and Santa Monica Boulevard, whilst the black and white Sylvester Stallone portrait ad was spied along Wilshire Boulevard on July 10, 2014.
If you're a fan of the action film franchise, be sure to also check out this billboard for The Expendables and the outdoor ad campaign for The Expendables 2 to see how the impressive cast has grown over time.
Maybe in the future we'll see action heroes Dwayne Johnson and Vin Diesel join the cast (although maybe not until the sixth or seventh movies). And then there's always the likes of Steven Seagal, Nicholas Cage and John Travolta.
The possibilities are endless, but they are going to need a bigger billboard.