Question

I am forty years. Find error and correct it

Answer 1

I am forty years old is correct

"I am forty years" is not a complete and proper sentence

Answer 2

Answer:

I am forty years old.

Explanation:

The explanation is that when you say that "I am forty years" , you are basically sating that you are the 'years' that you just mentioned. So stating 'old' after 'years' is an important grammatical trend in English even though it is common sense to understand what you're implying by "I am forty years".

It is just like saying the Hindi equivalent of "Mai chalis sal hu." instead the reasonably correct one would be: "Mai Chalis sal ka/ki hu."  

Therefore, the right sentence here, declarative in nature, would be "I am forty years old".

PS: The correct spelling of 40 is always 'forty' it is not 'fourty' in any form of English. F O R T Y. Don't trust people who mention it is "fourty". My Thanks : )