damn, you ask tough questions, but here goes.

well, if I remember correctly, the earth is 93,000,000 miles from the sun. so we will take this 93,000,000 miles as the radius of a roughly circular orbit. pi = approx 3.1416. The circumference of a circle is 2 x pi x radius = 2 x 3.1416 x 93,000,000 = 584,337,500 miles, this is the distance the earth travels around the sun in one year.

so the number of hours in 1 year is 365x24 = 8760. The earth completes an orbit of the sun in one year, therefore the approximate orbital speed of the earth around the sun is 584,337.500 / 8760 = 66,705 miles per hour.

multiply by 1.6 to get km/h of 106,728 kmh.

I am sorry, but I forget the conversion formula to convert standard hours into metric units.

How am I doing so far?