Hurry Up Hermeneutic: Forgiveness

I've always thought that since seven times seventy was 490, and since I Corinthians 13 says that love keeps no records of wrongs, then we are supposed to always forgive our brothers, no matter how many times they sin against us.  Now, this is true, but this is not why it's true.  I understand that this is a bit of splitting hairs, but I think that proper hermeneutics and exegesis is extremely important, so I have learned that Peter was asking Jesus if they should forgive their brother once each day, and Jesus responded, "no, you should forgive them seventy times each day."  Now, since it would be really hard for someone to sin against you seventy times in one day, then you should always forgive your brother, no matter how many times they sin against you.  I Corinthians 13 is now not necessary to understand Matthew 18, but it does provide a bonus:  confirmation of the clear teaching in Matthew.