1. Explain the "sub-circuit" feature of CircuitVerse. What does it do?

It allows for you to insert a circuit that you've built in the same project, into another circuit in the same project.

2. Explain why we need 4 inputs for this circuit, when we only needed 3 for the Date of Birth circuit.

We need 4 inputs instead of just 3 inputs simply because we are counting in binary in this circuit. In the Date of Birth circuit we we not counting in binary rather we were just plugging in inputs for a particular, chosen number to be displayed

3. What was the trickiest or most difficult part of this assignment? Why?

Actually plugging in the truth table correctly for the decoder, as to why... let's just say I was being an idiot, hahaha. I had to re-plug it like, idk, about 5 times I would say. Aah, I was so stupid, but the rest was fairly easy to do.