Ask HN: Acquisition after 1.5yrs

So we are a startup that was launched 1.5yrs ago. We are working on some exciting stuff, are bootstrapped so far and are generating revenue.

Now we got approached by a fortune 500 company that wants to acquire us. This is my first time as a founder to be on this type of call, so didn't really know how to respond.

We told them that we are open to acquisition talks and then they told me to come back to them with a dollar amount.

Now I am not sure how to come up with that dollar amount. Clearly, they are not buying us for our revenue. This is a technology play.

How should I go about putting a number to it?

Thanks.