How many edges does a forest with n trees and v vertices

Question

Question: 1. What is the smallest number greater than n that is ≡ 1 (mod n)? For a number k between 1 and n, what is the smallest number larger than k but also ≡ k (mod n)?

2. Let f: N×N → N, with f(a,b) = a² +b². Decide (with proof) whether f is one-to-one, onto, both, or neither.

3. How many edges does a forest with n trees and v vertices (and vi vertices in the ith tree) have?