There has been debate whether cheap downloads will count when determining chart positions but the Official Charts Company has confirmed they will.
It says: "The rules do not specify a minimum retail selling price for the sale of a single to be eligible for inclusion. However, they specify a minimum published dealer price (what a retailer pays a record label for the song).
"This does not affect the ability of a retailer to carry out price promotions. Any genuine consumer purchases made as a result of a retailer promotion will be eligible as long as the single meets all other applicable chart rules."
Download for free (one per facebook account) and your download will count towards the chart: