Here is one of those great article/slideshows:
The math on seven and 8 are just fantastic #-o
http://innovationforendurance.msn.com/slideshows/detail/running/254985356 (http://innovationforendurance.msn.com/slideshows/detail/running/254985356)
Incase your wondering:
Lake michigan is much larger then .49 meters or .54 yards
and the panama canal is not .3 meters long or about 1 foot