Answer: The Nominal Interest rate, which is how fast the dollar value of savings grows
Step-by-step explanation:
Banks advertise the Nominal Interest rate. This is the rate that measures purely, how much return is received or paid if one lends out money or borrows money respectively.
It is therefore the value at which savings grow.
It is not adjusted for inflation yet but when adjusted is called the REAL INTEREST RATE.
It is important to note that when Banks advertise the Nominal rate, it is not yet adjusted for fees or the compounding of interest.