"Berapa kata ada di kalimat itu?"
Can't you also say this as /Berapa kata dalam kalimat itu?/
I'm pretty sure you can also say this as /Berapa kata ada di dalam kalimat itu?/
Why don't we need "di" in front of the "dalam" here?" Is it optional or just wrong? And why?
I think it's just optional. If you were being very formal, you might use the /di/. But most don't in casual speech.
Does perkataan mean the same thing?