how do you add two numbers from messages?

let's say I send a 5
then I send a 10
(via messages)

I need an object to remember 5, then add 10, result of 15.

in other words, I need to send a series of numbers to an object and have it add the numbers every time.

any object for this?

just tried accum. I was able to accomplish this by sending a 0 to the first inlet to clear the value after I'm done adding numbers. This works.