How inflation or delfation is calculated:
What does $100 in 1980 dollars equal today?
Step 1:
2011 Anchorage CPI
divided by
1980 Anchorage CPI
201.4
--------------
85.5
= 2.35
Step 2:
Multiply 2.35 by any number of 1980 dollars and you will have the 2011 equivalent.

(100 x 2.35= $235)

So, $235 in 2011 would have the same purchasing power as $100 did in 1980.
The formula can be reversed to deflate current dollars. Use the quick deflation calculator in excel.