390,000 20年(240個月)每月還款:
390000 * 6.80%/12 * (1+6.80%/12) 240/[(1+6.80%/12) 240-65438]
說明:240是240的冪。
390,000 30年(360個月)每月還款:
390000 * 6.80%/12 * (1+6.80%/12) 360/[(1+6.80%/12) 360-65438.
說明:360是360次方。