To answer this question, you'll need to project the values of the cost of every memory on the table:
The rule is to fill in the blanks using half of the number preceding the slot we want to fill, it's a matter of pattern recognition. Take note, the two tables are one splited due to insufficient spacing.
The cost of 1GB is $ 0.25. I prefer the doubling of the lower numbers to get the higher ones because the pattern is easy to spot and apply.
