Earth is approximately 93 000 000 mi from the sun. It revolves around the sun, in an almost circular orbit, in about 365 days. Calculate the

365 days = 365*24 hours

Circumferential distance travelled in 365*24 hours = 2*pi*93,000,000 miles

Linear speed = distance/time = 2*pi*93,000,000/(365*24) miles per hour

$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}{\mathtt{\,\times\,}}{\mathtt{93\,000\,000}}}{\left({\mathtt{365}}{\mathtt{\,\times\,}}{\mathtt{24}}\right)}} = {\mathtt{66\,705.049\: \!494\: \!029\: \!856\: \!433\: \!1}}$$

speed = 66,705.05 miles per hour to nearest hundredth (or did you mean to nearest hundred, in which case speed = 66,700 miles per hour).

.

Assuming that Earth's orbit is circular . . .

Circumference = pi times diameter

Since the sun is the center, the diameter is 2*93000000 = 186000000

C = pi*186000000 = 584336233.5677 miles.

So every 365 days Earth travels 584336233.567701542 miles.

Every 1 day it must travel 584336233.5677/365 =  1600921.187856717 miles.

And every hour 1600921.1878/24 = 66705.049494030 miles.

The speed is 66,705.05 miles/hour (nearest hundredth) 

WOW.  That is really fast!     

And the cops book us for speeding!!