Of course Paddy is almost correct! It IS a small number.
The Circumference of a Circle is Pi x Diameter. We do not need to know the diameter as we do know that we are increasing it by 1 inch. Therefore the extra length needed is Pi x 1inch which equals 3.142 inches.
Seems ridiculous but it is absolutely true. Pddy's mistake is he used radius instead of diameter. (Area of a circle is Pi x R2
Here is the maths
24.000 miles = 1,520,640,000 inches. Therefore diameter = that divided by 3.142 which equals 483,971,992.4 inches
Increase diameter by 1 inch gives 483,971,993.4 then x 3.142 gives 1,520,640,003.142
Extra length 3.142 inches! Well done Paddy- you're the closest - 2 Brownie Points for the effort!