isn't it if we loan 150K, the expected payment (after 25/30years) is like 300K..

so, if after 10 years you already pay 150k.. that means you're left with around 150K balance.. When you're trying to pay the loan early, then they'll redo the calculation.. gives rebates etc.

Actually, i don't know much about this loan calculation.. but I know that after including interest, the loan is roughly double the original amount..