Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the 10. If the decimal is being moved to the right, the exponent will be negative. If the decimal is being moved to the left, the exponent will be positive.
If you plug in the radius (0.5 because the radius is half of the diameter) and the height to the formula for volume of a cylinder you will get pi•0.5 squared•15 which when solved is 11.775.
