About 8000 b.c.e. the first grinding stone, called a quern, was invented in Egypt, and the first grain was crushed. The modern Indian chapatis, made from unleavened whole wheat flour, and Mexican tortillas, made from corn, resemble the breads produced at that time.
Dimple on a golf ball create a thin turbulent boundary layer of air that clings to the ball'surface. This allows the smoothly flowing air to follow the ball's surface a little farther around the back side of the ball, there by decreasing the size of the wake
Achemical change(chemical reaction) is achangeof materials into other, new materials with different properties, and one or more new substances are formed. Burning of wood is achemical changeas new substances which cannot be changed back (j.g. carbon dioxide, water vapor) are formed
My answer is: The first known calculating device was ABACUS