How can I construct a finite automaton for even decimal numbers?

Question

I have to do this exercise and am completely stumped as to how. I've constructed some FA's before, but using binary numbers. How can I do this but for even decimal numbers?

Answer 1

It would be a simple one.

2 states: q1, q2.

• q1 is initial state.
• q2 is final state.
• if input digit on q1 is any even digit, make a move to q2.
• if input digit on q1 is any odd digit, remain on q1.
• if input digit on q2 is any even digit, remain on q2.
• if input digit on q2 is any odd digit, make a move back to q1.