Out of the 500 marbles that Cindy had, she gave her four friends 80 marbles each. What's four times the number of marbles she has remaining? Let's think first. Chain of thought:
Cindy gave her four friends 80 marbles each, a total of 4 * 80 = 320 marbles. She was left with 500 - 320 = 180 marbles. Four times the number of marbles she has remaining is 180 * 4 = 720.
Therefore, the answer is 720.