Compare beach areas: 2×2=4sq ft.
1 mile=5280 ft, so ½mile=2640ft.
3 miles=15840ft. Area of Long Beach=15840×2640.
Divide by 4 to find out how much Long Beach is bigger than the small beach area=15840×2640÷4=10,454,400.
So we would expect this number times 30 shells=313,632,000 shells approximately.
For quantitative estimates call this 300 million shells.