How do you use dimensional analysis to figure out how many seconds are in 4 years?

All there is behind the solution is the constant stream of multiplying. This is what is all about. A conversion from one unit to another requires some sort of multiplier to change one unit to another.

Here is a list of these multipliers. ##1"in"=2.54"cm"## ##1"lb"=0.453592"kg"## ##1 " second"=1/60 "minute"##

If you want to switch these, all you need to do is to divide the non-one value with itself and the 1 to find the other, vice versa solution.

##1"cm"=0.393701"in"## ##1"kg"=2.20462"lb"## ##1 " minute"=60 " seconds"##

From there, we are ready to move on. 1 minute = 60 seconds 1 hour = 60 minutes ##60" seconds" xx 60" minutes"=3600 " seconds"=1" hour"##

24 hours = 1 day 365.25 days = 1 year (to account for leap years, the likelihood of the extra day out of 4 years is added.)

##3600" seconds" xx 24" hours" = 86,400" seconds"##

...and finally: ##86,400" seconds" xx 365.25" days" xx 4=## ##126,230,400" seconds"##