How do you find how old a turtle is?

A scute is what makes a turtles shell look quilted. About once a year each individual scute sheds, revealing a new one under neath and also leaves a layer on the new one. If you count the layers on a scute then you can tell about how old the turtle is. Example. 2 layers = 2 years old, 10 layers = 10 years old. If the turtle has no layers then the turtle is less than a year old.