Math Helps Me Know Where to Direct My Rage Let’s talk about greed. Specifically: the greed that is interest on home mortgage loans. As with many things, this blog post is inspired by a tweet. This time, it is my own: Sometimes I love to hate on interest. Let's say you buy a house for $300k, for a roundish number. * 20% down is $60k, but if you do 15% it's $45k and you can "save" that $15k for "my house surprised me with entropy"