1. Two thousand and forty kilograms is equivalent to two million and four hundred thousand grams.2. The gram (g) is the basic unit of mass, while the kilogram (kg) is a larger unit of mass, with one gram approximately equal to 0.501x10^23 times the mass of a C-12 atom.3. The kilogram is one of the seven base units of the International System of Units (SI), first established by the French Academy of Sciences during the French Revolution.4. Relevant conversions for mass are as follows: - 1 ton = 1,000,000 grams (one million grams) - 1 kilogram (kg) = 1,000 grams (one thousand grams) - 1 jin (市斤) = 500 grams (1 gram = 0.002 jin) - 1 milligram = 0.001 gram (1 gram = 1,000 milligrams) - 1 microgram = 0.000001 gram (1 gram = 1,000,000 micrograms) - 1 nanogram = 0.000000001 gram (1 gram = 1,000,020,399 nanograms)