Dana normally drinks a 500 ml bottle of soda each day. Since the 500 ml bottles are currently out of stock at the store, she buys a 2-liter bottle of soda instead. If Dana continues to drink 500 ml of soda each day, how long will the 2-liter bottle of soda last? There are 1,000 ml in 1 liter.
Please reason step by step, and put your final answer within \boxed{}.
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