



 
Hi Fred. To convert this to something more familiar, you can first convert it to cubic feet: 1 mile = 5280 ft, so (1 mile)^{3} = (5280 ft^{3}) = 5280^{3} ft^{3} = 147197952000 ft^{3}. Now we can convert that to some more familiar volume measures. Each foot is 3.048 decimeters (dm) and since 1 dm^{3} is a litre, we have: 147197952000 ft^{3} = 147197952000 (3.048 dm)^{3} = 147197952000 x (3.048^{3}) litres = 4168181825441 litres. If you prefer US gallons, you need to look up the conversion: 1 ft^{3} = 7.48051948 US gallons, so 147197952000 ft^{3} = 147197952000 (7.48051948 US gallons) = 1101117147352 US gallons. Big numbers like these are rather hard to picture. That's about as much water as flows over Niagara Falls in about a month. Another comparison: The land area of Manhattan Island in New York City is 22.96 square miles. So if we divide 1 cubic mile by 22.96 square miles, we have 1/22.96 miles = 230 ft. So if you built a retaining wall Cheers,  


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