Find the sum of the First $50$ Natural Numbers starting from $11$. Is it from $11-50$ or $11-60$? This a simple question yet confusing for me, I found the answer as 1220 by taking sum from $11$ to $50$, by inferring the question as first 50 natural numbers {$1,2,3,4,5,6,7,8,9,10,11,...49,50$} 

and sum starting from 11 which means sum $= 11+12+...+49+50$. 
But my friend says otherwise, he took from 11 to 60 and says answer as 1775. Can anyone explain how to infer the word first in the context of maths.
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.

To clarify why I believe both interpretations are valid:


"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,\ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term.

Here the first term is $11$ and $50$th term  is $60$, so the sum is
$$50\times\frac{11+60}2=1775.$$