Question

what vectors have a magnitude of 4?

Answer 1

vectors that have |v|=4
so if we have v=<4> then |v|=4
if we think 2-dimensional vectors we have
any vector v=<a,b> such that |v|=sqrt(a^2+b^2)=4 is a vector with mag of 4.

Answer 2

you can go all the way to n-dimensions