Example 4 (continued)

a scale) of 365 days to 4,500,000,000 years.  If "n" represents this unknown "number of days," we can write/express a pertinent relation (amongst the four quantities) as the following proportion: Multiplying each side by 4,500,000,000 yr and then simplifying will yield the following results and value for (our number of days) n... Being less than one whole day, this tells us that the time in question should fall onDecember 31st,as Jan.1st represents the beginning time and the last moment on the very last day in the calendar year corresponds to now (i.e., 4½ billion years later).  Carrying our problem a wee

bit further, the time of day can also be found, by converting 0.365 days to hours and then moving backwards from 12:00 midnight this amount of time in hours... Finally, we can assign even a time of day to the event where humans first emerged. Subtracting 9 hours from 12:00 midnight gives us 3 o'clock in the afternoon.  Thus, in our calendar year scale model where the Earth formed at the first instant on January 1st, our human ancestors only arrived sometime shortly after 3:00 p.m. on December 31st.

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     Okay, we've gotten a glimpse into the scope of the diverse arena wherein proportions can be a wonderful tool.  Whether it be to better understand financial matters such as purchasing the better buy between two competing products, how a property tax is determined, or space-time matters on a scale of millions and billions, those previously annoying fractions are beginning to appear a worthwhile commodity to have in our arsenal.
     In the last example, we dealt with very large numbers which have a multitude of zeros in them. You may remember (from a previous math