If the High Rate Method makes the most mathematical sense, why would anyone use Snowball Method instead? It saves more money in interest
It increases the number of debts you have to repay
It increases the number of monthly payments that you need to make
It is behaviorally motivating

It is behaviorally motivating

Explanation:

High Rate method and Snowball method are two different tactics that people can use to pay off their debt.

In High Rate method, we pay the debt that possess high interest rates first  before we handle the ones that have lower interest. Since interest rates will keep accruing the more you left the debt unpaid, paying the one that has higher interest first make the most mathematical sense.

In snowball method, We pay the debt that has the smallest balance first regardless of the interest rates.

Snowball method does not have as strong of financial incentive as the high rate method. But, paying the debts that have the smallest balance first will make the debtor able to cross one type of debts off their book in a much faster rate.

Psychologically, this tend to be more rewarding since it provide a list of small victories that keep the debtors motivated to steadily cutting off their debts.