In 2016, 128 gigabytes (GB) of portable computer memory cost $32.
Here is a double number line that represents the situation:
One set of tick marks has already been drawn to show the result of multiplying 128 and 32 each by 12. Label the amount of memory and the cost for these tick marks.
Next, keep multiplying by 12 and drawing and labeling new tick marks, until you can no longer clearly label each new tick mark with a number.