Typically, plywood sheets are four feet by eight feet
It depends on how big a sheet of plywood you are talking about.
It depends on the size of the plywood sheets.
Depends on the size of the sheets of plywood.
One, if it is big enough.
3/4 inch plywood takes 48 sheets to make a unit.
584 / 8 = length of 146 sheets of plywood laid end to end
One can find good prices on plywood sheets by visiting the auction website eBay. One can also find good prices on plywood sheets by visiting the websites Wickes and Jewson.
124.7 sheets
Assuming the plywood comes in 4' by 8' sheets you would need 6 sheets to cover a 12' by 16' area.
Divide the area of the windows by the area of the sheets. Note: 3x5 and 2x4 are not areas, they are numbers. And you don't say how big the sheets are, so it is difficult to be helpful.
80 sheets
Plywood comes in 4 x 8 sheets = 32 sq ft 300/32 = 9.37 so you need 10 sheets