The metric system is based on powers of 10. Ten increments of one unit make up the next larger unit.
The size discrepancy between 100,000 and 10,000,000 may not be obvious. Observe that 100,000 = 10^5 and 10,000,000=10^7. Exponent difference (7-5=2) shows that the larger number is 10^2, or 100 times bigger than the smaller number.
There are units of mass, distance, area, pressure, electric and current. Some units are "composed" of others. For instance, density (d) is expressed as mass/volume (d= m/v). Therefore, in standard units, density is grams (mass) per cubic centimeter (volume).
The "kilo" of kilogram is a prefix example. Mass of 1 kilogram is equivalent to one thousand grams because "kilo" prefix corresponds to 10^3 of the standard unit---in this case, the gram.
Tiny sizes, distances, energies and weights require prefixes that indicate minuscule fractions (such as one millionth) of base units. Tables illustrate metric prefixes from the smallest (femto-) to the largest (tera-) that can be combined with standard units.