the intensity increases by a factor of 10, the Ritcher scale uses a logarithm with base 10. For example an earthquake with magnitude 2 is 10^2 times more intense than a standard earthquake, while an earthquake with magnitude 3 is 10^3 times more intense than a standard earthquake, and 10^3 = 10^2 • 10
Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; in terms of energy, each whole number increase corresponds to an increase of about 31.6 times the amount of energy released, and each increase of 0.2 corresponds to approximately a doubling of the energy released.
In first calculation Miranda was first calculating tax of a 7% of 19$ tennis racket and than she added it to cost of tennis racket. In second calculation she automatically calculated 107% of a price of tennis racket that she will pay at register.
