Write the Word or Phrase That Best Completes Each Statement $$8 + 16 + 24 + \ldots + 8 n = 4 n ( n + 1 )$$

Write the word or phrase that best completes each statement or answers the question. Use mathematical induction to prove that the statement is true for every positive integer n.
- $$8 + 16 + 24 + \ldots + 8 n = 4 n ( n + 1 )$$