Need help with calculator. Hard stuck

That’s the link to my code sandbox. I am trying to make it with hooks, without adding redux or anything like that.

I can get one round of math to pass, but I can’t get step 9, 13. Can someone take the time to explain to me what I need to do next?
I have no clue how to proceed.

Hey Ivan,

you can have a look at the tests here:

Let us know if this helps you to solve it on your own.

I get the jist of the tests. But can’t really make it out to get the logic for my project. I don’t have a lot of experience making tests.