help with the word Numb

I am currently confused by the word "Numb." To demonstrate my confusion please read the following two sentences:

"His left hand was more numb than his right hand."

"His left hand was number than his right hand."

Which sentence is correct? Normally I would be inclined to choose the second sentence but I am thrown off by the word "number" as it makes me think of "a number" (i.e. 23). This is where I am confused.