Because people try and annualise the weekly rent by multiplying by 52.
That's wrong.
It's 52 1/7 weeks in a normal year and 52 2/7 weeks in a leap year.
Divide by 12 and there's the problem.
e.g. $100pw = $5214.29pa (not $5200) = $434.52pcm (not $433.33pcm)
