With a ruler.
In metric because you can't use feet, or something.
"In inches because they have no feet" Close enough I guess
My other answer would have been, "Cut it in half, measure one half, then multiply by 2."
I like snakes and have one as a pet so I like that answer less
I like snakes too! That answer is in the vein of the, "Sure I know how many cows are in that herd: 468!" "How'd ya do that so fast?" "Simple, just count the legs and divide by 4."
Separate names with a comma.