Your Profit = (Selling Price) - (Cost of Unit)
In a trading period, a seller may sell anywhere from zero to the maximum number of units available to sell. Sellers earn money by selling units at prices that are above their costs. Profits are computed by subtracting each unit's cost from its selling price. Therefore,
For example, suppose the cost of the first unit is $5.00 and the cost of the second unit is $8.00. Suppose you sell the 1st unit for $7.00 and the second unit for $9.50. You do not sell any other units this period. Your profits are:
profit from 1st unit = $7.00 - $5.00 = $2.00
profit from 2nd unit = $9.50 - $8.00 = $1.50
total earnings for the period = $2.00 + $1.50 = $3.50
Note that sellers do not incur the cost for a unit unless they sell the unit. Also, sellers can make negative profits if they sell at a price lower than cost. The computer will keep track of all trades and earnings.