Convert them into set builder form

(vi) F = The set of all letters in the word BETTER
Write the following sets in the set-builder form:
(i) (3, 6, 9, 12}
(ii) {2, 4, 8, 16, 32}
(iii) {5, 25, 125, 625}
(iv) {2, 4, 6 ,...}
(v) {1, 4, 9 ,...,100}