(b) the product obtained by multiplying:
(i) the amount referred to in paragraph (a)
by
(ii) the amount, adjusted in such manner as may be prescribed and rounded to the nearest one-thousandth, or, where the result obtained is equidistant from two consecutive one-thousandths, to the higher thereof, that is determined by the formula
(A/B) - 1
where
A
is the Consumer Price Index for the 12 month period that ended on September 30 next before that year, and
B
is the Consumer Price Index for the 12 month period immediately preceding the period mentioned in the description of A.