mass of water is easy. it's density is 1.
D = mass / volume. so we've got
1 = x / 700,000,000
anything divided by itself is one. so that means for every cc (cubic centimeter or millimeter), water weighs one gram.
700,000,000 cubic miles. I convert it to cubic feet, which is 3.696E12. convert to cubic centimeters, and you've got
1.04659065004E17. or 104,659,065,004,000,000. 104.5 quadrillion cm^3.
just replace cm^3 with grams, yuo've got your wieght.
it's
1.04659065004E14, or 104,659,065,004,000 trillion kilograms.
104.6 trillion kilograms < 6 heptillion (?) kilograms.
the earth's wieght is 57,329,004,418, or 57 billion, times heavier.
i think i got all my math right.
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