One cubic centimeter (1.0 cm3) of water has a mass of 1.0 10-3 kg.
(a) determine the mass of 1.0 m3 of water

One meter has 100cm. One cubic meter is therefore 100cm x 100cm x 100cm, multiplied are 1,000,000 cubic centimeters.Water density of 1.0x10^-3 Kg per cubic centimeter MULTIPLIED BY 1.00x10^6 (one million) cubic centimeters equals 1.0x10^3Kg or 1000Kg or one metric ton.I multiplied because I wanted to cancel the cubic centimeter from "the denominator of the density units with the numerator of the volume units"

No it doesnt because it can be any number.