Well... we know that... there are 365 days in a year, unless is a leap-year, but we'll use 365 anyway
and each day has 24hrs, each hr has 60 minutes
so. let us use those ratios
so.. multiply and simplify, cancelling out any like-units atop and bottom
notice, all we do, is use the ratios, in a way, that if we need one unit to be changed, we flip the ratio
for example, to toss away "year" unit, since in the first fraction is at the bottom, then we put it on the top on the ratio, year/year = 1, effectively cancelling the unit
