What is "Mill Rate" and how is it calculated. Here's what Wikipedia says:

The property tax rate is typically given as a percentage. It may be expressed as a per mil (amount of tax per thousand currency units of property value), which is also known as a millage rate or mill (one-thousandth of a currency unit). To calculate the property tax, the authority multiplies the assessed value by the mill rate and then divides by 1,000. For example, a property with an assessed value of $350,000 located in Fairfield with a mill rate of 25.82 mills would have a property tax bill of $9,037 per year. 

A property assessed at $2,500,000 would have a property tax bill of $64,675