Simple Aggregate Method

The simplest way to combine the prices of several commodities into one index number is to add up all their base-year prices, add up all their current-year prices, and compare the two totals. This is the Simple Aggregate Method.

To apply the formula: list every commodity's base-year price and current-year price, add each column separately to get $\Sigma p_0$ and $\Sigma p_1$, divide the current-year total by the base-year total, and multiply by 100. …