Car Lease Payment Calculator

Hey, When on a lease / financial calculator when buying a car, what does "the estimated value of trade" and how am I suppose to decide?

I went to the site and Mercedes Benz has been using the calculator on rent ML350 (MSRP: $ 40.525)

When I return payment: 15,000
Estimated value of trade: 10,000 (im taking a stab at what that means)
Lease Term: 48 months.
Miles per year: 15,000

Monthly payments out only $ 31 per month ... somehow I just do not see that as being correct ... But if I change the estimated trade value to 0, the monthly payments is 269.

I just want to know what "trade value is estimated. I think: This is the value of the car when the lease expires.

A trade-in means essentially U where trade a car for another, so when you ask what is the (approximate trade-in value) YOU ARE Estimating the value or cost of the car you are trading and that goes to the downpayment
Example: U PUT $ 15,000 cash
YOUR EXCHANGE car is worth: $ 10,000
YOUR practical implementation of $ 25,000 cash

AND how it affects your payment, the payment over U DOWN THE WORLD, THE LOW monthly payments are.