Songs and Comparisons

I love to listen to songs and try to find Bible verses that they are based off of. I recently heard another song called 7 times 70, which refers to forgiveness which is in Matthew 18:21-22. The same kind of message is in Luke 17:3-4. In Matthew, Peter asked if you forgive someone 7 times and Jesus says to forgive them 77 times even if they don't ask for forgiveness. Certain versions say "70 times 7 times" instead. In Luke, He says that you are to forgive them when they ask for forgiveness. This verse says that you forgive your brother only if he is sorry.
While the messages are mainly the same, there are some major differences. If you read other verses, you can tell that you're not just supposed to forgive someone when they ask to be forgiven but are to forgive because God has forgiven us. You would think that this point would be an important reminder for us even though it doesn't sound that way.
The number 7 is the perfect number. The number 77 is quite interesting. There were 77 generations between Adam and Jesus according to Luke 3. Another interesting way to think of the number is atomic numbers in chemistry. "The iridium, Ir, atomic number 77, is a white metal which the name is a derivative of the Greek word "iris" meaning" rainbow". It is under the sign of the rainbow that God concludes his Alliance between him and the humanity, and the Christian remains in this Alliance if he forgives 77 times the faults of his brothers (Mt 18,22)"(ridingthebeast.com).
Another thing I found interesting was that Luke was more of the compassionate Gospel but yet it says that you forgive someone only when they are sorry. I thought that the verses would have fit the trend if they were switched.
http://www.ridingthebeast.com/numbers/nu77.php