10.0.0.0/8 is correct, you can only use the last 24 bits. But nothing prevents you from breaking this class A in smaller networks!

That means that you can not use 10.0.0.0/7 (which would include 11.0.0.0) but you can use 10.0.0.32/30, that includes from 10.0.0.32 until 10.0.0.35.