Estimating Pi

When you drag the slider you will throw up to 250 darts at the target. All darts will land between (0,0), (2,0), (2,2) and (0,2). Some darts will also land within the circle. Why does 4 times the number of hits divided by the total number of darts approximate pi?

You can throw multiple sets by hitting the “throw again” button and track the results. What does increasing the number of darts do to the histogram?