Why your dog isn't the age you think

I mean, how the "multiply by 7" trick is derived is by a linearization of how old we are when we die divided by how old they are when they die. 70/10 = 7 (example, not sure what the numbers are) not exactly a bad estimate, kinda like a linear regression. Plus, it's easier for people to track how much longer their dogs have without going to their graphing calculator lol