Define with example forecasting. Actual sales for a product for the last $12$ months were as follows.

$\backslash$table$[[$Month$,$No$.$ of units sold,Month,No$.$ of units sold$],[1,800,7,1000],[2,500,8,1100],[3,900,9,1400],[4,1100,10,1500],[5,1300,11,1600],[6,1300,12,1800]]$

Calculate: Using a simple $3$ months moving average, make a forecast for the various months of the year.