Today I asked my dad how many seconds are in a century.
So he took out a piece of paper and we figured it out.
And here is our equation:
60sec/1minute · 60min/1hour · 24hours/1day · 365days/1year · 100years/1century = seconds in a century
This is called the factor-label method. All those fractions after the first one are actually equal to one.
When we multiply it out, most of the labels cancel out:
minute · 60 min/1 hour · 24 hours/1 day · 365 days/1 year · 100 years/1century = seconds in a century
Now we have to do the arithmetic:
60 · 60 · 24 · 365 · 100 = seconds in a century
We tried doing it on a calculator, but the answer was too big!
So we factored it:
36 · 24 · 365 · 104
And multiplied the first part on the calculator:
315,360 · 104
Then we added four zeroes:
There are over 3 billion seconds of in a one hundred year period!