haha well I had a quick shot at it, and my answer feels wrong so I will post it and have someone explain....

I have the circumference of the earth in metres as 40,000,000

> diameter<-40000000/pi

> diameter

[1] 12732395

so the diameter of this earth is 12732395

I am adding 1 metre stick to each radius, and 2 to the diamter and times by pi to get the new circumference;

> (diameter+2)*pi

[1] 40000006

giving 6 extra metres, which seems crazy...