It would be interesting to do the math on it. Say you have a debt payment budget of $500 / month for payments of $80, $100 and $200. Also, for sake of the exam

It would be interesting to do the math on it. Say you have a debt payment budget of $500 / month for payments of $80, $100 and $200. Also, for sake of the example assume that the amount owed on each is proportional to the payment size (smallest to largest). You have a total of $380 with an extra $120 to apply to one of the payments. You’ll apply it to the $80 payment until it’s paid off so you’re now paying $200 / month towards it. Once it’s paid off, you focus on the $100 / month but because the $80 has been paid off you now have an extra $200 / month so you can pay $300 / month today towards it. Once that is paid off, you can now focus the entire $500 towards the $200 / month payment. It would be interesting to see some models.