Updating from os 10 4 to 10 5
the Greeks used "myriad" for 10,000 while the Hebrew Bible named it "r'vavah," and in India "Lakh" still means 100,000, while "crore" is 10,000,000.
A 9-year old in 1920 coined the name "Googol" for 10 Back at the dim beginnings of humanity, "numbers" simply meant positive whole numbers ("integers"): one apple, two apples, three apples...
It is then convenient (for calculation, and also for applying logarithms) to separate the number into two parts--a number from 1 to 10, giving its structure, and a power of 10, giving the magnitude.
Electric charge, for instance, is measured in coulombs: about one coulomb flows each second through a 100-watt lightbulb.
Rational numbers are dense: no matter how close two of them are to each other, one could always place another rational number between them--for instance, half their sum is one choice out of many.
Decimal fractions which stop at some length are rational numbers too, though decimal fractions having infinite length but with a repeating pattern (0.33333..., 0.575757...