Can anyone help with this question?

let's say you have exactly twice as many bars as he. So you have 1340 and he has 670

So, as long as you have at least 1340, but fewer than 2009 bars, he has some, and you have at least twice as many.

Sorry, but it's wrong...

669

it is 670

it is actually 669

The answer is my name

I bet you got it from AoPS

i did

669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669 669

Since your friend receives at least $1$ chocolate bar, the maximum number of chocolate bars you can get is $2010 - 1 = 2009$. If you receive $n$ chocolate bars, then your friend gets $2010-n$ chocolate bars. Since you must have at least twice as many chocolate bars as your friend, we have the inequality\begin{align*}

n &\ge 2(2010-n) \\
\Rightarrow\qquad n &\ge 4020-2n \\
\Rightarrow\qquad 3n &\ge 4020 \\
\Rightarrow\qquad n &\ge 1340.
\end{align*}Therefore, you must keep a minimum of $1340$ chocolate bars. Therefore, the difference between the maximum and minimum number of chocolate bars you can have is $2009 - 1340 = \boxed{669}$.

I got this from AoPs and thats why i searched it up