Mr. Johnson owns an online store. The first month, the online store received 500 orders. For each month that followed, the number of orders the online store received was approximately 25% more than the number of orders received the previous month. Mr. Johnson writes this equation to model the approximate number of orders, y, received each month following the first month:
y=500(0.25)^x

There is an error in this equation. Describe the error that was made in this equation.